The β-D-methyl glycoside of<unk>  in the low energy 4C1 conformation of D-glucose<unk>  is a sugar<unk>  derived from glucose, with its sixth carbon atom oxidized to a carboxylic<unk> . In living beings, this primary oxidation occurs with UDP-α-D-glucose (UDPG), not with the free sugar.<unk> , like its precursor glucose, can exist as a linear (carboxo-)aldohexose (D-glucose are capable of forming two furanose forms (α and β) and two pyranose forms (α and β). By the Fischer convention,<unk>  has two stereoisomers (enantiomers), D- and L-glucuronic<unk> , depending on its configuration at C-5. Most physiological sugars are of the D-configuration. Due to ring closure, cyclic sugars have another asymmetric carbon atom (C-1), resulting in two more stereoisomers, named anomers. Depending on the configuration at C-1, there are two anomers of<unk> , α- and β-form. In β-D-glucuronic<unk>  the C-1 hydroxy group is on the same side of the pyranose ring as the carboxyl group. In the free sugar<unk> , the β-form is prevalent (~64%), whereas in the organism, the α-form UDP-α-D-glucuronic<unk>  (UDPGA) predominates. Carbohydrate stereoisomers, which differ in configuration at only one (other) asymmetric C-atom, are named epimers. For example, D-mannuronic (C-2), D-alluronic (C-3), D-galacturonic (C-4), and L-iduronic<unk>  (C-5) are epimers of<unk> . The nonplanar pyranose rings can assume either chair (in 2 variants) or boat conformation. The preferred conformation depends on spatial interference or other interactions of the substituents. The pyranose form of D-glucose and its derivative D-glucuronic<unk>  prefer the chair 4C1. Additional oxidation at C-1 to the carboxyl level yields the dicarboxylic glucaric<unk> . Glucuronolactone is the self-ester (lactone) of<unk> . Direct oxidation of an aldose affects the aldehyde group first. A laboratory synthesis of a uronic<unk>  from an aldose requires protecting the aldehyde and hydroxy groups from oxidation, for example by conversion to cyclic acetals (e. g., acetonides). Sodium glucuronate can be produced by the direct oxidation of starch with concentrated nitric<unk> . In this preparation the low availability of water keeps the starch polymers from hydrolyzing and only oxidizes the free hydroxyls, in much the same way that nitrogen dioxide would oxidize the starch. Once this reaction is complete, and the starch/nitric<unk>  mix turns clear (after giving off nitrogen dioxide<unk> s), the solution can be diluted, and hydrolyzed with another mineral<unk> . Then the oxidation is slowly quenched with sodium hydroxide (or sodium bicarbonate), forming sodium glucuronate, which can be crystallized out of solution.With transition metals, it forms complexes such as iron(III) glucuronate, iron(II) glucuronate, and copper(II) glucuronate.
Glucuronic acid
Hyaluronic acid
Cerebroside
Glabrene
Lactose
Methyl cellulose
Iminosugar
Glycogen