 Discovering the tertiary structure of a protein , or the quaternary structure of its complexes , can provide important clues about how the protein performs its function . Common experimental methods of structure determination include X @-@ ray crystallography and NMR spectroscopy , both of which can produce information at atomic resolution . However , NMR experiments are able to provide information from which a subset of distances between pairs of atoms can be estimated , and the final possible conformations for a protein are determined by solving a distance geometry problem . Dual polarisation interferometry is a quantitative analytical method for measuring the overall protein conformation and conformational changes due to interactions or other stimulus . Circular dichroism is another laboratory technique for determining internal β @-@ sheet / α @-@ helical composition of proteins . Cryoelectron microscopy is used to produce lower @-@ resolution structural information about very large protein complexes , including assembled viruses ; a variant known as electron crystallography can also produce high @-@ resolution information in some cases , especially for two @-@ dimensional crystals of membrane proteins . Solved structures are usually deposited in the Protein Data Bank ( PDB ) , a freely available resource from which structural data about thousands of proteins can be obtained in the form of Cartesian coordinates for each atom in the protein . 
 Discovering the tertiary structure of a protein , or the quaternary structure of its complexes , can provide important clues about how the protein <a href='uninflect' title='1'><mark>performs</mark></a> its function . Common experimental methods of structure determination include X @-@ ray crystallography and NMR spectroscopy , both of which can produce information at atomic resolution . However , NMR experiments <a href='drop_aux' title='2'><mark>are</mark></a>able to provide information from which a subset of distances between pairs of atoms can be estimated , and the final possible conformations for a protein are determined by solving a distance geometry problem . Dual polarisation interferometry <a href='drop_aux' title='3'><mark>is</mark></a>a quantitative analytical method for measuring the overall protein conformation and conformational changes due to interactions or other stimulus . Circular dichroism <a href='drop_aux' title='4'><mark>is</mark></a>another laboratory technique for determining internal β @-@ sheet / α @-@ helical composition of proteins . Cryoelectron microscopy is used to produce lower @-@ resolution structural information about very large protein complexes , including assembled viruses ; a variant known as electron crystallography can also produce high @-@ resolution information in some cases , especially for two @-@ dimensional crystals of membrane proteins . Solved structures are usually deposited in the Protein Data Bank ( PDB ) , a freely available resource from which structural data about thousands of proteins can be obtained in the form of Cartesian coordinates for each atom in the protein . 
Discovering da tertiary structure of a protein , or tdaquaternary structure of its complexes , can provide important clues about how thdarotein perform its function . Common experimental methods of structure determination include X @-@ ray crystallography and NMR spectroscopy , both of which can produce information at atomic resolution . However , NMR experiments able to provide information from which a subset of distances between pairs of atoms can be estimated , and thedanal possible conformations fa a protein are determined by solving a distance geometry problem . Dual polarisation interferometry a quantitative analytical method ffirmeasuring the darall protein conformation and conformational changes due to interactions or other stimulus . Circular dichroism anotha laboratory technique ffirdetermining internal β @-@ sheet / α @-@ helical composition of proteins . Cryoelectron microscopy is used to produce lower @-@ resolution structural information about very large protein complexes , including assembled viruses ; a variant known as electron crystallography can also produce high @-@ resolution information in some cases , especially ffirtwo @-@ dimensional crystals of membrane proteins . Solved structures are usually deposited in the Protein Data Bank ( PDB ) , a freely available resource from which structural data about thousands of proteins can b obtained in the fda of Cartesian coordinates ffireach atom in the protein .