how disulphide bonds are formed between sulfhydryl groups
Active site


cofactor and are used to break the disulphide bond during the catalytic reaction. NADPH is bound by three positively charged residues: Arg-218, His-219 and Arg-224. The catalytic process starts when the FAD is reduced by NADPH to accept one electron and from FADH.It then attacks the disulphide bond formed between 2 cysteine residues, forming one SH bond and a single S group. This S group will act as a nucleophile to attack the disulphide bond in the oxidised glutathione(GSSG), breaking it and forming a cysteine-SG complex.The first SG
16423898
Biotinylation


a reduced level of biotinylation is required. Sulfhydryl-reactive groups such as maleimides, haloacetyls and pyridyl disulfides, require free sulfhydryl groups for conjugation; disulfide bonds must first be reduced to free up the sulfhydryl groups for biotinylation. If no free sulfhydryl groups are available, lysines can be modified with various thiolation reagents (Traut's reagent, SAT(PEG4), SATA and SATP), resulting in the addition of a free sulfhydryl. Sulfhydryl biotinylation is performed at a slightly lower pH (6.5-7.5) than labeling with NHS esters
488897
Hypochlorous acid


groups. This is because HClO oxidises sulfhydryl groups, leading to the formation of disulfide bonds that can result in crosslinking of proteins. The HClO mechanism of sulfhydryl oxidation is similar to that of chloramine, and may only be bacteriostatic, because once the residual chlorine is dissipated, some sulfhydryl function can be restored. One sulfhydryl-containing amino acid can scavenge up to four molecules of HOCl. Consistent with this, it has been proposed that sulfhydryl groups of sulfur-containing amino acids can be oxidized a total of three times by
13892378
Escherichia coli in molecular biology


used successfully to produce proteins previously thought difficult or impossible in "E. coli", such as those containing multiple disulfide bonds or those requiring post-translational modification for stability or function. The cellular environment of "E. coli" is normally too reducing for disulphide bonds to form, proteins with disulphide bonds therefore may be secreted to its periplasmic space, however, mutants in which the reduction of both thioredoxins and glutathione is impaired also allow disulphide bonded proteins to be produced in the cytoplasm of "E. coli". It has also
16488556
Active site


side chain is oxidised and two glutathione molecules are connected by a disulphide bond to form a dimer(GSSG). In order to regenerate glutathione the disulphide bond has to be broken, In human cells, this is done by glutathione reductase(GR). Glutathione reductase is a dimer that contains two identical subunits. It requires one NADP and one FAD as the cofactors. The active site is located in the linkage between two subunits. The NADPH is involved in the generation of FADH-.In the active site, there are two cysteine residues besides the FAD
16423897
Cysteine


covalently bonded to other cysteine residues to form disulfide bonds, which play an important role in the folding and stability of some proteins, usually proteins secreted to the extracellular medium. Since most cellular compartments are reducing environments, disulfide bonds are generally unstable in the cytosol with some exceptions as noted below. Disulfide bonds in proteins are formed by oxidation of the sulfhydryl group of cysteine residues. The other sulfur-containing amino acid, methionine, cannot form disulfide bonds. More aggressive oxidants convert cysteine to the corresponding sulfinic acid and sulfonic
7706492
Model lipid bilayer


or disulphide group that forms a covalent bond with gold, forming self assembled monolayers (SAM). The limitation of the intra-membrane mobility of supported lipid bilayers can be overcome by introducing half-membrane spanning tether lipids with benzyl disulphide (DPL) and synthetic archaea analogue full membrane spanning lipids with phytanoly chains to stabilize the structure and polyethyleneglycol units as a hydrophilic spacer. Bilayer formation is achieved by exposure of the lipid coated gold substrate to outer layer lipids either in an ethanol solution or in liposomes. The advantage of this
13252523
Helenalin


the group of sesquiterpene lactones which are characterised by a lactone ring. Beside this ring, the structure of helenalin has two reactive groups (α-methylene-γ-butyrolactone and a cyclopentenone group) that can undergo a Michael addition. The double bond in the carbonyl group can undergo a Michael addition with a thiol group, also called a sulfhydryl group. Therefore, helenalin can interact with proteins by forming covalent bonds to the thiol groups of cysteine-containing proteins/peptides, such as glutathione. This effect can disrupt the
13191019
Cyanogen bromide


react with the imine to cleave the peptide bond, forming a homoserine lactone and new C-terminal peptide. However, if the adjacent amino acid to methionine has a hydroxyl or sulfhydryl group, this group can react with the imine to form a homoserine without peptide bond cleavage. These two cases are shown in the figure. Cyanogen bromide is a common reagent in organic synthesis. As stated earlier, the reagent is prone to attack by nucleophiles such as amines and alcohols because of the electrophilic carbon. In the synthesis of cyanamides
9223693
Fibronectin


weight, disulfide-bonded multimers. The mechanism of formation of these multimers is not presently known. Plasma fibronectin has been shown to contain two free sulfhydryls per subunit (X), and cellular fibronectin has been shown to contain at least one. These sulfhydryls probably are buried within the tertiary structure, because sulfhydryls are exposed when the fibronectin is denatured. Such denaturation results in the oxidation of free sulfhydryls and formation of disulfide-bonded fibronectin multimers. This has led to speculation that the free sulfhydryls may be involved in formation of
15175276
Acetyl-CoA


the sulfhydryl substituent of the β-mercaptoethylamine group. This thioester linkage is a "high energy" bond, which is particularly reactive. Hydrolysis of the thioester bond is exergonic (−31.5 kJ/mol). CoA is acetylated to acetyl-CoA by the breakdown of carbohydrates through glycolysis and by the breakdown of fatty acids through β-oxidation. Acetyl-CoA then enters the citric acid cycle, where the acetyl group is oxidized to carbon dioxide and water, and the energy released is captured in the form of 11 ATP
17217472
Fibronectin


disulfide-bonded fibronectin multimers in the extracellular matrix. Consistent with this, sulfhydryl modification of fibronectin with N-ethylmaleimide prevents binding to cell layers. Tryptic cleavage patterns of multimeric fibronectin do not reveal the disulfide-bonded fragments that would be expected if multimerization involved one or both of the free sulfhydryls. The free sulfhydryls of fibronectin are not required for the binding of fibronectin to the cell layer or for its subsequent incorporation into the extracellular matrix. Disulfide-bonded multimerization of fibronectin in the cell layer occurs by disulfide bond exchange in
15175277
Dc1a


Dc1a (β-diguetoxin or DTX9.2) is a potent insect-selective poisonous 57-residue peptide that is produced by the desert bush spider "(Diguetia canities)." It promotes the opening of voltage-gated Na channels (Na) in German cockroach "(Blattella germanica)" by interacting with the paddle motif in domain II. Dc1a contains two β-sheets and one β-hairpin loop whereas the sheets are hold together by four disulphide bonds. Three of these four disulphide bonds form a classical cysteine knot region (
9422741
Active site


anion is released and then receives one proton from adjacent SH group and from the first glutathione monomer. Next the adjacent S group attack disulphide bond in cysteine-SG complex and release the second SG anion. It receives one proton in solution and forms the second glutathione monomer. Chymotrypsin is a serine endopeptidase that is present in pancreatic juice and helps the hydrolysis of proteins and peptide. It catalyzes the hydrolysis of peptide bonds in L-isomers of tyrosine, phenylalanine, and tryptophan. In the active site of this enzyme, three
16423899
Urease


assumes an intermediate tetrahedral orientation. The breakdown of this intermediate is then helped by a sulfhydryl group of a cysteine located near the active site. A hydrogen bonds to one of the nitrogen atoms, breaking its bond with carbon, and releasing an NH3 molecule. Simultaneously, the bond between the oxygen and the 6-coordinate nickel is broken. This leaves a carbamate ion coordinated to the 5-coordinate Ni, which is then displaced by a water molecule, regenerating the enzyme. The carbamate produced then spontaneously degrades to produce another ammonia and carbonic acid
6431564
Thiol


A physical manifestation of cysteine-cystine equilibrium is provided by hair straightening technologies. Sulfhydryl groups in the active site of an enzyme can form noncovalent bonds with the enzyme's substrate as well, contributing to covalent catalytic activity in catalytic triads. Active site cysteine residues are the functional unit in cysteine protease catalytic triads. Cysteine residues may also react with heavy metal ions (Zn, Cd, Pb, Hg, Ag) because of the high affinity between the soft sulfide and the soft metal (see hard and soft acids and bases
3553124
Fibrillin 1


change affecting conserved cysteine of the CaB-EGF-like domain encoded by exon 13 of the FBN1 gene can cause MFS to develop. Higher frequency and severity of MFS occurs when there are incorrect substitutions at the C1-C2 or C3-C4 disulphide bonds, therefore, correct cysteine localisation and disulphide bonding at these loci are critical to structural integrity. Mutations in the FBN1 gene resulting in incorrect bonding at the C5-C6 disulphide bond generally results in MFS of lesser severity. Concentrated mutations of the CaB-EGF domain along the FBN1 polypeptide affects MFS severity
4765535
Protein–protein interaction


while some G-coupled receptors, such as muscarinic receptor M3, pre-couple with G proteins prior to the receptor-ligand binding. Interactions between intrinsically disordered protein regions to globular protein domains (i.e. MoRFs) are transient interactions. Covalent interactions are those with the strongest association and are formed by disulphide bonds or electron sharing. Although being rare, these interactions are determinant in some posttranslational modifications, as ubiquitination and SUMOylation. Non-covalent bonds are usually established during transient interactions by the combination of weaker bonds, such as
12833224
Type IV collagen C4 domain


formation. In network assembly, the C4 trimers of two protomers interact, forming a C4 hexamer structure, to select and connect protomers. The collagen IV C4 domain contains 12 cysteines, and all of them are involved in disulphide bonds. It folds into a tertiary structure with predominantly beta-strands. The collagen IV C4 domain is composed of two similarly folded subdomains stabilised by 3 intrachain dissulphide bonds involving the following pairs: C1-C6, C2-C5, and C3-C4. Each subdomain represents a compact disulphide-stabilised triangular structure, from which
19220974
Hypochlorous acid


three HClO molecules, with the fourth reacting with the α-amino group. The first reaction yields sulfenic acid (R–SOH) then sulfinic acid (R–SOH) and finally R–SOH. Sulfenic acids form disulfides with another protein sulfhydryl group, causing cross-linking and aggregation of proteins. Sulfinic acid and R–SOH derivatives are produced only at high molar excesses of HClO, and disulfides are formed primarily at bacteriocidal levels. Disulfide bonds can also be oxidized by HClO to sulfinic acid. Because the oxidation
13892379
Zingibain


have investigated potential methods to inactivate the free sulfhydryl group within the enzyme’s active site. Mechanistic possibilities include oxidizing the sulfhydryl, exchanging it with disulfide bridges, forming quinone-thiol adducts, or binding the sulfhydryl to a heavy metal ion. 0.2% sodium ascorbate was found to stabilize zingibain for up to 14 days at 5 °C, whereas comparable concentrations of EDTA and CaCl had minimal impact on stability. Zingibain has been observed to deactivate itself through autolysis, which can be pre-empted by reacting the active sulfhydryl group
21894586
Hydrophobin


4 disulphide bonds. They are able to reverse the wettability of surfaces by spontaneous self-assembly of the monomeric proteins into amphipathic monolayers at hydrophobic:hydrophilic surfaces. Despite this common feature, hydrophobins are subdivided into two classes based on differences on their monomeric structure, such as the spacing between the cysteine residues, and based on the different physicochemical properties of the amphipathic monolayers they form. Extensive structural analyses of individual hydrophobins from the two classes have elucidated that the morphological and physical differences between the class I and class II polymer forms
7702062
Peptide synthesis


C-terminus at some suitable point allows on-resin cyclization by amide bond formation with the deprotected N-terminus. Once cyclization has taken place, the peptide is cleaved from resin by acidolysis and purified. The strategy for the solid-phase synthesis of cyclic peptides in not limited to attachment through Asp, Glu or Lys side chains. Cysteine has a very reactive sulfhydryl group on its side chain. A disulfide bridge is created when a sulfur atom from one Cysteine forms a single covalent bond with another sulfur atom from a
5910823
Glucokinase


at 28% of capacity at the usual threshold glucose for triggering insulin release. The sulfhydryl groups of several cysteines surround the glucose binding site. All except cys 230 are essential for the catalytic process, forming multiple disulfide bridges during interaction with the substrates and regulators. At least in the beta cells, the ratio of active to inactive glucokinase molecules is at least partly determined by the balance of oxidation of sulfhydryl groups or reduction of disulfide bridges. These sulfhydryl groups are quite sensitive to the oxidation status of the cells, making glucokinase
8122333
Chemotherapy


and semustine (MeCCNU), fotemustine and streptozotocin. Tetrazines include dacarbazine, mitozolomide and temozolomide. Aziridines include thiotepa, mytomycin and diaziquone (AZQ). Cisplatin and derivatives include cisplatin, carboplatin and oxaliplatin. They impair cell function by forming covalent bonds with the amino, carboxyl, sulfhydryl, and phosphate groups in biologically important molecules. Non-classical alkylating agents include procarbazine and hexamethylmelamine. Anti-metabolites are a group of molecules that impede DNA and RNA synthesis. Many of them have a similar structure to the building blocks of
7417034
Protease inhibitor (biology)


inhibitor undergoes a conformational change forming an almost perfect alpha-helix from Asn2 to Met32 in the active site cleft of the peptidase. The peptidase inhibitor family I36 domain is only found in a small number of proteins restricted to "Streptomyces" species. All have four conserved cysteines that probably form two disulphide bonds. One of these proteins from "Streptomyces nigrescens", is the well characterised metalloproteinase inhibitor SMPI. The structure of SMPI has been determined. It has 102 amino acid residues with two disulphide bridges and specifically inhibits metalloproteinases such
11035304
Two-dimensional materials


-direct in a bilayer. Hafnium Disulphide is a group IVB TMD with formula . Like other TMDs, it possess a layered structure with strong covalent bonding between the Hf and S atoms in a layer and weak Van der Wall forces between layers. The compound has type structure and is an indirect band gap semiconducting material. The interlayer spacing between the layers is 0.56 nm, which is small compared to group VIB TMDs like , making it difficult to cleave its atomic layers. However, recently its crystals with large interlayer spacing has
15945380
Covalitoxin-II


residues which form three disulphide bonds, between the specific amino acid locations 2&16, 19&21 and 15&28. There is an equal distribution of hydrophilic, hydrophobic and neutral amino acids. Near the C-terminus there is a positively charged surface formed by conserved basic residues, which is thought to interact with an ion channel. The inhibitor cystine knot motif that is formed by the cysteine residues shows analogy to other spider toxins and can also be found in ω-conotoxins, which are present in the venom of cone snails. It has
5582196
Disulfide


of the S−S bond, which is usually the weakest bond in a molecule. In the Zincke disulfide cleavage reactions, disulfides are cleaved to give a sulfenyl halide by reaction with bromine or chlorine. Disulfide bonds can be formed under oxidising conditions and play an important role in the folding and stability of some proteins, usually proteins secreted to the extracellular medium. Since most cellular compartments are reducing environments, in general, disulfide bonds are unstable in the cytosol, with some exceptions as noted below, unless a sulfhydryl oxidase is present.
17958247
Disulfide


, the standard reduction potential for ferrodoxins is about −430 mV. Disulfide bonds are usually formed from the oxidation of sulfhydryl (−SH) groups, especially in biological contexts. The transformation is depicted as follows: A variety of oxidants participate in this reaction including oxygen and hydrogen peroxide. Such reactions are thought to proceed via sulfenic acid intermediates. In the laboratory, iodine in the presence of base is commonly employed to oxidize thiols to disulfides. Several metals, such as copper(II) and iron(III) complexes affect this reaction. Alternatively, disulfide
17958238
Sulfoxylic acid


. Sulfoxylic acid can be made in the gas phase in an electric discharge through a neon, H, SO mixture. This also yields some sulfhydryl hydroperoxide. Sulfoxylic acid is an isomer of sulfinic acid, which has a hydrogen atom bonded to the sulfur, and the oxygen connected with a double bond (HS(O)OH). Other isomers are thiadioxyrane (a ring of two oxygen atoms and a sulfur), dihydrogen sulfone (a sulfur atom linked to two hydrogen and two oxygen atoms), sulfhydryl hydroperoxide (HSOOH), and
15416803
Interleukin


of normal and transformed avian cells of the myeloid lineage. Cytokines of the IL6/GCSF/MGF family are glycoproteins of about 170 to 180 amino acid residues that contain four conserved cysteine residues involved in two disulphide bonds. They have a compact, globular fold (similar to other interleukins), stabilised by the two disulphide bonds. One half of the structure is dominated by a 4-alpha-helix bundle with a left-handed twist; the helices are anti-parallel, with two overhand connections, which fall into a double
13335299
EMI domain


be a protein-protein interaction module, as the EMI domain of EMILIN-1 was found to interact with the C1q domain of EMILIN-2. The EMI domain possesses six highly conserved cysteine residues, which likely form disulphide bonds. Other key features of the EMI domain are the C-C-x-G-[WYFH] pattern, a hydrophobic position just preceding the first cysteine (Cys1) of the domain and a cluster of hydrophobic residues between Cys3 and Cys4. The EMI domain could be made of two sub-domains, the fold of
6407779
Dc1a


ICK). ICK region is common in spider toxins and provides chemical, thermal and biological stability to the protein. Although this region is evolutionary conserved in the spiders family, it has remarkable differences with other ICK-like proteins. One of the special characteristics is that Dc1a contains an additional disulphide bond that links cysteine 42 with cysteine 45 and stabilizes the serine-rich hairpin loop. Another feature is a unique three-standard antiparallel β-sheet in the amino-terminal region which is formed by an unusually large loop between
9422742
DNA-functionalized quantum dots


surface of a quantum dot coated in zinc sulfide. Single strands of DNA can then be modified with an added amino group in order to covalently bond to the carboxyl group, due to an amide bond formed between the carboxyl and amino groups in the presence of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC). Factors that can influence the binding of single stranded DNA to the carboxyl group are pH and ionic strength. The pH determines how many protons are available to form covalent bonds, with less being present as the pH gets higher. This results in
4216804
2-Iminothiolane


2-Iminothiolane is a cyclic thioimidate compound also known as Traut's reagent. It is a thiolating reagent that reacts with primary amine groups, such as those of amino acids, to form sulfhydryl groups. 2-Iminothiolane reacts with primary amines efficiently at pH 7 to 9, creating aminidine compounds with a sulfhydryl group. Thus it allows for crosslinking or labeling of molecules such as proteins through use of disulfide or thioether conjugation. It was first used to thiolate a subunit of ribosome in "E. coli" in 1973 by Robert Traut, its namesake
7397747
Cook–Heilbron thiazole synthesis


the synthesis of a 5-aminothiazole from an α-aminonitrile and carbon disulphide, a lone pair on the nitrogen of the α-aminonitrile performs a nucleophilic attack on the slightly electropositive carbon of carbondisulfide. This addition reaction pushes electrons from the carbon-sulfur double bond onto one of the sulfur atoms. Acting as a Lewis Base, the sulfur atom donates its electrons to the carbon atom of the nitrile, forming a sulfur-carbon sigma bond in an intramolecular 5-exo-dig cyclization. This cyclization forms a 5-imino-2-thione thiazolidine compound that undergoes
13710066
Hypochlorous acid


active ingredient in bleach. HClO is a stronger oxidant than chlorine under standard conditions. HClO reacts with HCl to form chlorine gas: HClO reacts with amines to form chloramines and water. Reacting with ammonia: HClO can also react with organic amines, forming "N"-chloroamines. Hypochlorous acid reacts with a wide variety of biomolecules, including DNA, RNA, fatty acid groups, cholesterol and proteins. Knox "et al." first noted that HClO is a sulfhydryl inhibitor that, in sufficient quantity, could completely inactivate proteins containing sulfhydryl
13892377
Cysteine


in the [NiFe]-hydrogenases. The sulfhydryl group also has a high affinity for heavy metals, so that proteins containing cysteine, such as metallothionein, will bind metals such as mercury, lead, and cadmium tightly. In the translation of messenger RNA molecules to produce polypeptides, cysteine is coded for by the UGU and UGC codons. Cysteine has traditionally been considered to be a hydrophilic amino acid, based largely on the chemical parallel between its sulfhydryl group and the hydroxyl groups in the side chains of other polar amino acids. However,
7706489
CUB domain


carbohydrate groups on the glycoproteins found on the surface of oocytes. The spermadhesins from pigs, bulls and stallions show 40-98% similarity in their amino acid sequences and all possess a disulphide bond between adjacent cysteine residues. The porcine spermadhesin polypeptides are coded by five closely linked genes. Bovine spermadhesin relies on a significantly lower number of genes with only two being associated with expression of this protein in bovine seminal fluid. Redundant genetic coding for spermadhesins have been observed in chimpanzees, dogs, and humans. The region correlating to spermadhesin
4162796
Molybdopterin synthase


Z, and the addition of two side chain sulfhydryl groups . E-coli "MPT synthase" is activated by the formation of a thiocarboxylate group at the second glycine of its C-terminal Gly-Gly motif, which serves as the sulfur donor for the formation of the diothiolene group in MPT . That is, the mechanism on "MPT synthase" depends on the interconversion between the activated form of MoaD with the thiocarboxylate group and the MoaE protein In the final step of MoCo biosynthesis, molybendum is incorporated to MPT by
4526962
Cysteine


. In plants and bacteria, cysteine biosynthesis also starts from serine, which is converted to "O"-acetylserine by the enzyme serine transacetylase. The enzyme O-acetylserine (thiol)-lyase, using sulfide sources, converts this ester into cysteine, releasing acetate. The cysteine sulfhydryl group is nucleophilic and easily oxidized. The reactivity is enhanced when the thiol is ionized, and cysteine residues in proteins have pK values close to neutrality, so are often in their reactive thiolate form in the cell. Because of its high reactivity, the sulfhydryl group of
7706486
Complement component 5a


a number of inflammatory diseases. Human polypeptide C5a contains 74 amino acids and has 11kDa. NMR spectroscopy proved that the molecule is composed of four helices and connected by peptide loops with three disulphide bonds between helix IV and II, III. There is a short 1.5 turn helix on N terminus but all agonist activity take place in the C terminus. C5a is rapidly metabolised by a serum enzyme carboxypeptidase B to a 72 amino acid form C5a des-Arg without C terminal arginine. C5a is an anaphylatoxin, causing increased expression of
11548917
Neuroplastic effects of pollution


these two metals will have is highly dependent upon the individual due to genetic variations. Mercury and lead are particularly neurotoxic for many reasons: they easily cross cell membranes, have oxidative effects on cells, react with sulfur in the body (leading to disturbances in the many functions that rely upon sulfhydryl groups), and reduce glutathione levels inside cells. Methylmercury, in particular, has an extremely high affinity for sulfhydryl groups. Organomercury is a particularly damaging form of mercury because of its high absorbability Lead also mimics calcium, a very
12182867
Protein metabolism


the ability of these amino acids to form hydrogen bonds so arginine and lysine that are methylated have different properties than their standard counterparts. Phosphorylation often occurs to serine, threonine, and tyrosine and involves replacing a hydrogen on the alcohol group at the terminus of the R group with a phosphate group. This adds a negative charge on the R groups and will thus change how the amino acids behave in comparison to their standard counterparts. Disulfide bond formation is the creation of disulfide bridges (covalent bonds) between two cysteine amino acids in
9119658
Nematode Her-1


In molecular biology the nematode Her-1 protein is a protein which adopts an all-helical structure with two subdomains: amino acids 19-80 comprise a left-handed three-helix bundle with an overhand connection between the second and third helices, whilst amino acids 81-164 comprise a left-handed anti-parallel four-helix bundle in which the first helix consists of four consecutive turns of 3-10-helix. Fourteen cysteines are conserved in all known HER-1 sequences and form seven disulphide bonds. The protein dictates male development in
19221025
Aequorin


show that all three calcium-binding sites are active but only two ions are needed to trigger the enzymatic reaction. Other studies have shown the presence of an internal cysteine bond that maintains the structure of aequorin. This has also explained the need for a thiol reagent like beta mercaptoethanol in the regeneration of the protein since such reagents weaken the sulfhydryl bonds between cysteine residues, expediting the regeneration of the aequorin. Chemical characterization of aequorin indicates the protein is somewhat resilient to harsh treatments. Aequorin is heat resistant. Held at 95⁰C for
10855891
Sclerotin


forming the different components of its body. For example, the stiffening of the biting surfaces of a locust's hard mandibles will not be the same as the stiffening of its springy hind tibiae. In general however, it is formed by cross-linking the various protein molecules with phenolic compounds; a tanning process under enzymatic control. In some of the Apterygota however, at least some of the cross-linking is by disulphide bonds reminiscent of protein cross-linking in the formation of keratin. This has led many authors to
10472049
Insulin receptor


or homo-dimerisation is maintained covalently between chains by a single disulphide link and between monomers in the dimer by two disulphide links extending from each α-chain. The overall 3D ectodomain structure, possessing four ligand binding sites, resembles an inverted ‘V’, with the each monomer rotated approximately 2-fold about an axis running parallel to the inverted 'V' and L2 and FnIII-1 domains from each monomer forming the inverted 'V's apex. The insulin receptor's endogenous ligands include insulin, IGF-I and IGF-II
19671599
Dimethylargininase


in vitro by antioxidants, which preserve the activity of DDAH. The sensitivity of DDAH to oxidative stress is conferred by a critical sulfhydryl in the active site of the enzyme that is required for the metabolism of ADMA. This sulfhydryl can also be reversibly inhibited by NO in an elegant form of negative feedback. Homocysteine (a putative cardiovascular risk factor) mounts an oxidative attack on DDAH to form a mixed disulfide, inactivating the enzyme. By oxidizing a sulfhydryl moiety critical for DDAH activity, homocysteine and other risk factors cause ADMA to
14735703
Cerato-platanin


surface proteins, is able to self-assemble "in vitro". CP is a 120 amino acid protein, containing 40% hydrophobic residues. It is one of the rare examples of protein in which contains a Hopf link. The link is formed by covalent loops - the pieces of protein backbone closed by two disulphide bonds (formed out of four cysteine residues). The N-terminal region of CP is very similar to cerato-ulmin, a phytotoxic protein produced by the "Ophiostoma" species belonging to the hydrophobin
20387817
Expression vector


are also available for a wide variety of needs. Other bacteria used for protein production include "Bacillus subtilis". Most heterologous proteins are expressed in the cytoplasm of "E. coli". However, not all proteins formed may be soluble in the cytoplasm, and incorrectly folded proteins formed in cytoplasm can form insoluble aggregates called inclusion bodies. Such insoluble proteins will require refolding, which can be an involved process and may not necessarily produce high yield. Proteins which have disulphide bonds are often not able to fold correctly due to the
11034660
Peptidoglycan recognition protein 1


three pairs of conserved cysteins which form three disulphide bonds. PGLYRP1 can form homodimers for its antimicrobial activity, and can complex with HSP70 for its cytotoxic activity. The PGLYRP1 protein plays an important role in the innate immune response. It is bactericidal against gram-positive bacteria such as "S. aureus, S. epidermidis," and "L. monocytogenes" and generally has proinflammatory effects, inducing TNF-a and IFN-g in many tissues. PGLYRP-1 is also known to form a cytotoxic complex with HSP-70, suggesting it may also
5258569
Cytochalasin B


, DNA-adduction might be a plausible reaction afterwards. A more suitable reaction seems to be the one with thiol-groups of several biomolecules. The thiol-groups would then no longer be available for disulphide bonds for further actin polymerization and thus a crucial step in actin polymerization is inhibited as the barbed ends of the filaments are blocked. An analogue principle is used by the well-studied capping proteins which are responsible for a natural limiting factor of actin polymerization. The first step in actin polymerization, after polymerization is initiated
4580250
Biotinylation


from 4-37 °C, pH values in the reaction range from 7-9, and incubation times range from a few minutes to 12 hours. Buffers containing amines (such as Tris or glycine) must be avoided, because they compete with the reaction. An alternative to primary amine biotinylation is to label sulfhydryl groups with biotin. Because free sulfhydryl groups are less prevalent on most proteins compared to primary amines, sulfhydryl biotinylation is useful when primary amines are located in the regulatory domain(s) of the target protein or when
488896
Fibroin


are linked by a disulphide bond, and P25 associates with disulphide-linked heavy and light chains by noncovalent interactions. P25 is plays an important role in maintaining integrity of the complex. The heavy fibroin protein consists of layers of antiparallel beta sheets. Its primary structure mainly consists of the recurrent amino acid sequence (Gly-Ser-Gly-Ala-Gly-Ala). The high glycine (and, to a lesser extent, alanine) content allows for tight packing of the sheets, which contributes to silk's rigid
13181370
Escherichia coli


produced in the periplasmic space or in the cytoplasm of mutants rendered sufficiently oxidizing to allow disulphide-bonds to form, while proteins requiring post-translational modification such as glycosylation for stability or function have been expressed using the N-linked glycosylation system of "Campylobacter jejuni" engineered into "E. coli". Modified "E. coli" cells have been used in vaccine development, bioremediation, production of biofuels, lighting, and production of immobilised enzymes. Strain K-12 is a mutant form of "E. coli" that over-expresses
18489386
Hypochlorous acid


of sulfhydryls and disulfides evolves hydrochloric acid, this process results in the depletion HClO. Hypochlorous acid reacts readily with amino acids that have amino group side-chains, with the chlorine from HClO displacing a hydrogen, resulting in an organic chloramine. Chlorinated amino acids rapidly decompose, but protein chloramines are longer-lived and retain some oxidative capacity. Thomas "et al." concluded from their results that most organic chloramines decayed by internal rearrangement and that fewer available NH groups promoted attack on the peptide bond, resulting in cleavage of the
13892380
Tityustoxin


are: TsTX-kα, a 37 amino acid, toxin gamma (TsTX-γ and TsTX-I) with 61 amino acid residues is the major neurotoxin of this venom. TsTX-Kβ has a longer chain. K+ channels blocking peptides are single chain polypeptides of 30-40 amino acids with three disulphide bridges. The toxin with four disulphide bonds is from TsTX-IV. This contains 41 amino acid residues. Two types of toxin are interesting: α-Scorpion toxins bind at site 3 of Na1 channels,
15304892
Cysteine-rich protein


Cysteine-rich proteins (also cysteine-rich peptide, CRP, disulphide-rich peptide) are small proteins that contain multiple internal disulphide bonds that cross-link them into their tertiary structure. CRPs include a highly conserved secretion peptide signal at the N-terminus and a cysteine-rich region at the C-terminus. CRPs are numerous in plants, with 756 CRP-encoding genes in the "Arabidopsis thaliana" genome. Several CRPs bind known receptors, but most CRP signaling mechanisms and protein interactions are uncharacterized. Characterized
2838861
Glycosidic bond


A glycosidic bond or glycosidic linkage is a type of covalent bond that joins a carbohydrate (sugar) molecule to another group, which may or may not be another carbohydrate. A glycosidic bond is formed between the hemiacetal or hemiketal group of a saccharide (or a molecule derived from a saccharide) and the hydroxyl group of some compound such as an alcohol. A substance containing a glycosidic bond is a glycoside. The term 'glycoside' is now extended to also cover compounds with bonds formed between hemiacetal (or hemiketal) groups
6797381
Late protein


A late protein is a viral protein that is formed after replication of the virus. One example is VP4 from simian virus 40 (SV40). In Human papillomavirus, two late proteins are involved in capsid formation: a major (L1) and a minor (L2) protein, in the approximate proportion 95:5%. L1 forms a pentameric assembly unit of the viral shell in a manner that closely resembles VP1 from polyomaviruses. Intermolecular disulphide bonding holds the L1 capsid proteins together. L1 capsid proteins can bind via its nuclear localisation
15494332
Liver-expressed antimicrobial peptide


Liver-expressed antimicrobial peptides are a family of mammalian liver-expressed antimicrobial peptides (LEAP). The exact function of this family is unclear. LEAP2 is a cysteine-rich, and cationic protein. LEAP2 contains a core structure with two disulphide bonds formed by cysteine residues in relative 1-3 and 2-4 positions. LEAP2 is synthesised as a 77-residue precursor, which is predominantly expressed in the liver and highly conserved among mammals. The largest native LEAP2 form of 40 amino acid residues is generated from the precursor at
18327189
Self-healing material


that can be reversibly cross-linked through oxidation and reduction. Under reducing condition, the disulfide (SS) bridges in the polymer breaks and results in monomers, however, under oxidizing condition, the thiols (SH) of each monomer forms the disulfide bond, cross-linking the starting materials to form the polymer. Chujo "et al." have shown the thiol-based reversible cross-linked polymer using poly("N"-acetylethyleneimine). (Scheme 5) A soft poly(urea-urethane) network uses the metathesis reaction in aromatic disulphides
8833566
Taipoxin


PLA toxin is Ca dependent for hydrolysing fatty acyl ester bonds at the sn-2 position of glycerol-phospholipids. Depending on disulphide bridge positions and lengths of C-termini these PLA enzymes/PLA toxins are categorized into three classes. These classes are also an indication of the toxicity of PLA/PLA, as PLAs from pancreatic secretions, bee venom or the weak elapid venoms are grouped into class I, whereas PLAs from the more potent viperid venoms which causes inflammatory exudate's are grouped into class II. However most snake venoms are
17037936
Agitoxin


triple-stranded antiparallel beta-sheet in which the C-terminal strand sits in the centre of the sheet, and a single alpha-helix covering one face of the beta-sheet (see image on the right). The cysteine side chains connect the beta-sheet and the helix via disulphide bonds to form the core of the molecule. The fold of agitoxin is homologous to the previously determined folds of scorpion venom toxins, classified as 'Scorpion short toxins' by Pfam. This fold, and the location of
15957333
Tenomodulin


C-terminal hydrophobic tail with eight Cys residues forming four disulphide-bridges, which are well conserved across vertebrate species. A smaller cyclic structure forming by single Cys280-Cys292 disulphide bridge in TNMD has been shown to exert an anti-angiogenic function, while the other three disulphide-bridges are speculated to hold this cyclic structure and C-terminal hydrophobic tail separated from each other to avoid the formation of intramolecular aggregates. In certain tendon tissues such as Achilles tendon and chordae tendineae cordis, 16 kDa cleaved C-terminal part of TNMD
19286884
Plecanatide


Glu. Disulphide bonds exist between Cys and Cys, as well as Cys and Cys. Plecanatide has two important motifs. The first being the acidic residues Asp and Glu which modulate the affinity for its receptor in response to environmental pH. Simulations predict the optimal activity of Plecanatide to occur at pH 5, making it suitable for targeting cells within the proximal intestine, which has a pH of between 5 and 6. The second is the ACTGC motif (residues Ala to Cys) which is the region responsible for its binding to the
10238301
Tamulotoxin


Tamulotoxin (or Tamulus toxin, Tamulustoxin, in short form: TmTx) is a venomous neurotoxin from the Indian Red Scorpion ("Hottentotta tamulus", "Mesobuthus tamulus" or "Buthus tamulus"). The toxin has been classified as a short-chain scorpion toxin. It consists of 36 amino acids and is referred to as TmTx1. A peptide consisting of 35 amino acids has also been identified, referred to as TmTx2. It possesses three intra-molecular disulphide bonds (S-S), leading to a
3155514
Thiophenol


oxygen atom is replaced by a sulfur atom. Thiophenols also describes a class of compounds formally derived from thiophenol itself. All have a sulfhydryl group (-SH) covalently bonded to an aromatic ring. The organosulfur ligand in the medicine thiomersal is a thiophenol. There are several methods of synthesis for thiophenol and related compounds, although thiophenol itself is usually purchased for laboratory operations. Methods are the reduction of benzenesulfonyl chloride with zinc. and the action of elemental sulfur on phenyl magnesium halide or phenyllithium followed by acidification. Via the Newman–
2237651
Crystallographic database


space group on the asymmetric unit. Visualization interfaces usually allow for switching between asymmetric unit and full structure representations. Bonds between atoms or ions can be identified by characteristic short distances between them. They can be classified as covalent, ionic, hydrogen, or other bonds including hybrid forms. Bond angles can be deduced from the bond vectors in groups of atoms or ions. Bond distances and angles can be made available to the user in tabular form or interactively, by selecting pairs or groups of atoms or ions. In ball-
20101301
Pectate lyase


lyase C ("pelC")1 from Erwinia chrysanthemi has been investigated in some detail. PelC contains a parallel beta-helix folding motif. The majority of the regular secondary structure is composed of parallel beta-sheets (about 30%). The individual strands of the sheets are connected by unordered loops of varying length. The backbone is then formed by a large helix composed of beta-sheets. There are two disulphide bonds in PelC and 12 proline residues. One of these prolines, Pro, is involved in a "cis
10885740
GSTK1


Glutathione S-transferase kappa 1 (GSTK1) is an enzyme that in humans is encoded by the "GSTK1" gene which is located on chromosome seven. It belongs to the superfamily of enzymes known as glutathione S-transferase (GST), which are mainly known for cellular detoxification. The GSTK1 gene consists of eight exons and seven introns and although it is a member of the GST family, its structure has been found to be similar to bacterial HCCA (2-hydroxychromene-2-carboxylate) isomerases and bacterial disulphide-bond-forming DsbA oxidoreductase
1874063
Structure and genome of HIV


(from a subset of patients that have been infected for many months to years) bind to or, are adapted to cope with, these envelope glycans. The molecular structure of the viral spike has now been determined by X-ray crystallography and cryo-electron microscopy. These advances in structural biology were made possible due to the development of stable recombinant forms of the viral spike by the introduction of an intersubunit disulphide bond and an isoleucine to proline mutation in gp41. The so-called SOSIP trimers not only reproduce the antigenic
2863751
Phosphaethynolate


the breaking of a bond. The shift towards the ketene isomer will also cause an increase in charge density on the elemental ‘E’ atom; this makes the elemental atom an increasing source of nucleophilicity "(see Figures 5 and 6)". The simplest analogue that can be formed as ‘X’ is varied is PCS. This anion was first isolated by Becker et al. by reacting the phosphaethynolate anion with carbon disulphide. Unlike PCO, PCS shows ambidentate nucleophilic tendencies towards the W(0) complex mentioned above. This
6447355
Nucleic acid structure


bond between their 9 nitrogen and the 1' -OH group of the deoxyribose. Cytosine, thymine and uracil are pyrimidines, hence the glycosidic bonds forms between their 1 nitrogen and the 1' -OH of the deoxyribose. For both the purine and pyrimidine bases, the phosphate group forms a bond with the deoxyribose sugar through an ester bond between one of its negatively charged oxygen groups and the 5' -OH of the sugar. The polarity in DNA and RNA is derived from the oxygen and nitrogen atoms in the backbone. Nucleic acids
912021
Isopeptide bond


a carboxy group on its side chain. These amino acids among other similar amino acids may join together or with some other amino acids to form an isopeptide bond. Isopeptide bond may also form between a γ-carboxamide group ( -(C=O)NH ) of glutamine and primary amine ( RNH ) of some amino acid as follows Bond formation can be either enzyme catalyzed, as in the case for the isopeptide bond formed between lysine and glutamine catalyzed by transglutaminases (their reaction is similar to the reaction above), or it can form
6562234
Agitoxin


the disulphide bonds, are a shared element between toxins stemming from arthropods. The structure of agitoxin-2, has been determined by NMR. Agitoxin binds to the Shaker "K" channel in "Drosophila" as well as to its mammalian homologue. It blocks this channel by binding with high affinity ("K" < 1 nmol/L) to its external vestibule. This high affinity to the ‘Shaker K’ channel is dependent on the residues of Arg , Lys , and Arg . The ability of the agitoxin to block
15957334
Phosphodiester bond


A phosphodiester bond occurs when exactly two of the hydroxyl groups in phosphoric acid react with hydroxyl groups on other molecules to form two ester bonds. Phosphodiester bonds are central to all life on Earth as they make up the backbone of the strands of nucleic acid. In DNA and RNA, the phosphodiester bond is the linkage between the 3' carbon atom of one sugar molecule and the 5' carbon atom of another, deoxyribose in DNA and ribose in RNA. Strong covalent bonds form between the phosphate group and two 5-carbon ring carbohydrates
20573305
Brazzein


follows: QDKCKKVYEN YPVSKCQLAN QCNYDCKLDK HARSGECFYD EKRNLQCICD YCEY" The structure of brazzein was determined by proton nuclear magnetic resonance (NMR) at a pH of 5.2 and 22 °C. Brazzein has four evenly spaced disulfide bonds and no sulfhydryl groups. 3D analysis of brazzein showed one alpha-helix and three strands of anti-parallel beta sheet. This is not superficially similar to either of the other two sweet-tasting proteins, monellin and thaumatin. However, a recent 3D study shows that these three proteins possess similar "sweet fingers
10069900
Dough conditioner


. Phosphoric acid, an acidulant, is used as a yeast stimulant. Calcium iodate, an oxidant, is a U.S. Food and Drug Administration "generally recognized as safe" or GRAS source of calcium. Dehydroascorbic acid and potassium bromate are oxidants, acting on sulfhydryl groups and disulfide bonds in wheat dough, in particular oxidizing glutathione. Potassium bromate acts more directly or with fewer chemical conversion steps than ascorbic acid. Glutathione increases wheat dough's extensibility, or relaxes it, while oxidizing a dough's glutathione increases elasticity. Like glutathione
11057269
Potassium arsenite


for the environment. The toxicity of potassium arsenite arises from arsenic’s high affinity for sulfhydryl groups. The formation of these arsenite-sulfur bonds impairs the functionality of certain enzymes such as glutathione reductase, glutathione peroxidases, thioredoxin reductase, and thioredoxin peroxidase. These enzymes are all closely affiliated with the defense of free radicals and the metabolism of pyruvate. Thus, exposure to potassium arsenite and other arsenite containing compounds results in the production of damaging oxygen free radicals and the arrest of cellular metabolism. Additionally, arsenite containing compounds have also
1166884
Trichorrhexis invaginata


LEKTI protein, resulting in genotype/phenotype correlations in cutaneous severity, susceptibility to atopic dermatitis, growth retardation, skin infection, increased stratum corneum protease activities, and elevated kallikrein levels in the stratum corneum. Trichorrhexis invaginata, or bamboo hair, is a hair shaft abnormality that occurs as a result of an intermittent keratinizing defect of the hair cortex. Incomplete conversion of the sulfhydryl –SH group onto S-S disulfide bonds in the protein of the cortical fibers leads to cortical softness and subsequent invagination of the fully keratinized distal hair
21921283
Melarsoprol


arsen-oxide that irreversibly binds to vicinal sulfhydryl groups on pyruvate kinase, which disrupts energy production in the parasite. The inability to distinguish between host and parasites renders this drug highly toxic with many side effects. Mel Ox reacts with trypanothione (a spermidine-glutathione adduct that replaces glutathione in trypanosomes). By binding to this adduct, it forms a melarsen oxide-trypanothione adduct (Mel T) that competitively inhibits trypanothione reductase, effectively killing the parasitic cell. Two arsenic-containing stereoisomers exist in a 3:1 molar ratio.
14881784
HIV


structure of the viral spike has now been determined by X-ray crystallography and cryogenic electron microscopy. These advances in structural biology were made possible due to the development of stable recombinant forms of the viral spike by the introduction of an intersubunit disulphide bond and an isoleucine to proline mutation (radical replacement of an amino acid) in gp41. The so-called SOSIP trimers not only reproduce the antigenic properties of the native viral spike, but also display the same degree of immature glycans as presented on the native virus. Recombinant trimeric
14367544
Epistasis


, polar and covalent). Epistatic interactions occur whenever one mutation alters the local environment of another residue (either by directly contacting it, or by inducing changes in the protein structure). For example, in a disulphide bridge, a single cysteine has no effect on protein stability until a second is present at the correct location at which point the two cysteines form a chemical bond which enhances the stability of the protein. This would be observed as positive epistasis where the double-cysteine variant had a much higher stability than either
1777876
Escherichia coli


of recombinant proteins in "E. coli". Researchers can introduce genes into the microbes using plasmids which permit high level expression of protein, and such protein may be mass-produced in industrial fermentation processes. One of the first useful applications of recombinant DNA technology was the manipulation of "E. coli" to produce human insulin. Many proteins previously thought difficult or impossible to be expressed in "E. coli" in folded form have been successfully expressed in "E. coli". For example, proteins with multiple disulphide bonds may be
18489385
Ornatin


In molecular biology, ornatin is a potent glycoprotein IIb-IIIa (GP IIb-IIIa) antagonist and platelet aggregation inhibitor isolated from "Placobdella ornata" (Turtle leech). The protein is 41-52 amino acids in length and contains the RGD recognition motif common in adhesion proteins, and 6 conserved cysteine residues. These form three disulphide bonds, which are required for activity. The sequences of ornatin B, C, D and E are highly similar, while A2 and A3 are less similar, lacking the N-
3706747
Homocystinuria


determination of methylmalonic acid should help to exclude cobalamin (vitamin B12) defects and vitamin B12 deficiency giving a differential diagnosis. The laboratory analysis of homocysteine itself is complicated because most homocysteine (possibly above 85%) is bound to other thiol amino acids and proteins in the form of disulphides (e.g., cysteine in cystine-homocysteine, homocysteine in homocysteine-homocysteine) via disulfide bonds. Since as an equilibrium process the proportion of free homocystene is variable a true value of total homocysteine (free + bound) is useful for confirming
8026829
TMEM8A


in the extracellular domain of membrane-bound proteins or in proteins known to be secreted. The EGF domain includes six cysteine residues which have been shown (in EGF) to be involved in disulphide bonds. The main structure is a two-stranded beta-sheet followed by a loop to a short C-terminal two-stranded sheet. Subdomains between the conserved cysteines vary in length. TMEM8A is found to be expressed ubiquitously throughout the human body; however, it has been shown to be downregulated during CD4+ and CD8
2893038
Western blot


the most common type of gel electrophoresis employs polyacrylamide gels and buffers loaded with sodium dodecyl sulfate (SDS). SDS-PAGE (SDS polyacrylamide gel electrophoresis) maintains polypeptides in a denatured state once they have been treated with strong reducing agents to remove secondary and tertiary structure (e.g. disulfide bonds [S-S] to sulfhydryl groups [SH and SH]) and thus allows separation of proteins by their molecular mass. Sampled proteins become covered in the negatively charged SDS, effectively becoming anionic, and migrate towards the positively charged
9012963
Cathelicidin


or two disulphide bonds. Even larger cathelicidin peptides (39-80 amino acid residues) are also present. These larger cathelicidins display repetitive proline motifs forming extended polyproline-type structures. The cathelicidin family shares primary sequence homology with the cystatin family of cysteine proteinase inhibitors, although amino acid residues thought to be important in such protease inhibition are usually lacking. Cathelicidin peptides have been found in humans, monkeys, mice, rats, rabbits, guinea pigs, pandas, pigs, cattle, frogs, sheep, goats, chickens,
6648934
Isotype (immunology)


around the body, appear at different stages of an adaptive immune response, and are often specialised to predominantly response to specific types of antigens via engagement of distinct soluble factors or immune effector cells. In humans, there are five heavy chain isotypes: IgM is the first immunoglobulin expressed during B cell development as a monomer on the surface of B naive cells. Upon antigenic stimulation, IgM+ B cells secrete multimeric IgM antibody which is formed by five Ig monomers are linked via disulphide bonds. The pentamer also contains a polypeptide J-
7756620
Glycoside hydrolase family 22


lactalbumin are similar both in terms of primary sequence and structure, and probably evolved from a common ancestral protein. Around 35 to 40% of the residues are conserved in both proteins as well as the positions of the four disulphide bonds. There is, however, no similarity in function. Another significant difference between the two enzymes is that all lactalbumins have the ability to bind calcium, while this property is restricted to only a few lysozymes. The binding site was deduced using high resolution X-ray structure analysis and was shown
17859063
Colipase


efficient dietary lipid hydrolysis. Efficient absorption of dietary fats is dependent on the action of pancreatic triglyceride lipase. Colipase binds to the C-terminal, non-catalytic domain of lipase, thereby stabilising an active conformation and considerably increasing the hydrophobicity of its binding site. Structural studies of the complex and of colipase alone have revealed the functionality of its architecture. Colipase is a small protein (12K) with five conserved disulphide bonds. Structural analogies have been recognised between a developmental protein (Dickkopf), the pancreatic lipase C-
3514259
Isopeptide bond


An isopeptide bond is an amide bond that can form for example between the carboxyl group of one amino acid and the amino group of another. At least one of these joining groups is part of the side chain of one of these amino acids. This is unlike in a peptide bond which is sometimes called an "eupeptide" bond, especially when discussing about both of these bond types in the same context to make a distinction between the two. Lysine for example has an amino group on its side chain and glutamic acid has
6562233
Phosphodiesterase 2


interact with hydrogen bond donators, which are part of amino acids in the active site of the enzyme and thereby contribute to the inhibition of the enzyme from hydrolyzing cAMP and cGMP similar to how the natural substrates bind to the active site. The structures of Bay 60-7550 and PDP are very similar ("see figure 4 and 5"). The difference between these molecules is the exocyclic methyl group on Bay 60-7550, which replaces the nitrogen atom in PDP decreasing the possibility to form hydrogen bonds with the enzyme
16784848
Serum free light-chain measurement


from bone marrow and lymph node cells. There is approximately 40% excess immunoglobulin light-chain production over immunoglobulin heavy-chain synthesis. Possibly this is simply to allow proper conformation of the intact immunoglobulin molecules, but an immunological role for the free light chains has also been proposed. There are approximately twice as many kappa-producing plasma cells as lambda plasma cells. Kappa free-light chains are normally monomeric, while lambda free-light chains tend to be dimeric, joined by disulphide bonds. Polymeric forms of both types
4657441
Iproniazid


toxification reaction that eventually can lead to the formation of an alkylating agent: the isopropyl radical. Hepatic necrosis was found in rats with doses as low as 10 mg/kg. The presence of the isopropyl radical was indicated by another observed product of the metabolism of iproniazid: the gas propane. Alkylating agents have the capability to bind to chemical groups such as amino, phosphate hydroxyl, imidazole and sulfhydryl groups. The formed isopropyl radical is able to form S-isopropyl conjugates "in vitro". This diminishes covalent binding to
11248637
MassMatrix


MassMatrix is a mass spectrometry data analysis software that uses a statistical model to achieve increased mass accuracy over other database search algorithms. This search engine is set apart from others dues to its ability to provide extremely efficient judgement between true and false positives for high mass accuracy data that has been obtained from present day mass spectrometer instruments. It is useful for identifying disulphide bonds in tandem mass spectrometry data. This search engine is set apart from others due to its ability to provide extremely efficient judgement between true and false positives for high mass
15060081