Of D-glucuronic acid

In contrast to L-iduronic acid residues, most of which are sulfated at C-2, D-glucuronic acid residues in heparin and heparan sulfate are largely or exclusively nonsulfated. This was especially proved by their susceptibility to periodate oxidation,123 and through characterization of D-glucuronic acid-containing di- and tetra-saccharides from deamina-tive104 109 110 138 or heparinase - heparanase cleavage137,145 of heparin. 

The amino sugar counterparts of D-glucuronic acid and nonsulfated L-iduronic acid in heparin are either N-acetylated, or nonsulfated at C-6, or both. 2-Acetamido-2-deoxy-D-glucosyl residues account for only a minor proportion of the total hexosamine in heparin, and are especially low in beef-lung preparations (see Table II).8,138,147 -149 In contrast, they... 

A number of derivatives of D-glucuronic acid have been made by Goebel and Babers37 with a view to their use in the synthesis of aldobionic acids. With the same object Owen, Peat and Jones38 prepared both pyranose and furanose derivatives of D-glucurone. 

Howell88 considered it to be a derivative of D-glucuronic acid, but this view was not confirmed by Charles and Scott,89 who isolated a crystalline barium heparinate from beef lung and detected the presence in it of an amino sugar. 

Mehltretter, C. L., The Chemical Synthesis of D-Glucuronic Acid, VIII, 231-249... 

Teague, Robert S., The Conjugates of D-Glucuronic Acid of Animal Origin, IX, 185-246... 

For the synthesis of D-glucuronic acid, methods of oxidation of suitable D-glucose derivatives have been devised during the past two decades these procedures have been comprehensively reviewed by Marsh,6 Mehltretter,7 and Heyns and Paulsen.8 For special purposes, for example, for the preparation of 6-I4C-labelled D-glucuronic acid, chain-extension reactions of 1,2-O-isopropylidene-a-D-xy/o-pen-todialdo-I,4-fiiranose by the cyanohydrin synthesis9 or by ethynyla-tion10 are used, but these frequently yield mixtures of D-glucuronic acid and L-iduronic acid. 

As the chemistry of D-glucuronic acid and its glycosides has already been reviewed,6 the present article is restricted to discussion... 

Glucuronidation involves the transfer of D-glucuronic acid from UDP-a-glu-curonic acid to an acceptor compound. The family of enzymes which catalyze this reaction are the UDP-glucuronyl transferases [16]. The reaction proceeds by nucleophilic Sn2 substitution of the C-1 carbon of glucuronic acid, the product undergoing inversion of configuration. The mechanism is illustrated schematically in Figure 7.21. 

Scheme 3.3 Chemoenzymatic conversion of D-glucuronic acid to L-ascorbic acid [59] NADPH-dependent uronate reductase A from Saccharomyces cerevisiae, cloned into . coli converted D-glucuronic acid at 90% yield. Chemical lactonization gave inter-...

In this clas of materials is grouped the majority of the seed mucilages, the acidity of which is due to a uronic acid (usually D-galacturonic acid) or to a methyl ether derivative of a uronic acid. This presence of D-galacturonic acid as the acidic component of the polysaccharide differentiates the mucilages from the gums, the acidity of the majority of which is due to the presence of D-glucuronic acid, or to one of its methyl ether derivatives (see above). 

Fig. 2 Structure of D-glucuronic acid (38) and P-D-glycopyranosyl barbiturates obtained from hexoses or D-glucuronic acid...

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