Glucuronic acid preparation

Isomers of D-apiofuranosyl 1-phosphate have been prepared by treating a mixture of jS-o-apio-D-furanosyl and /3-D-apio-L-furanosyl tetra-acetates with crystalline phosphoric acid. a-o-Apio-o- (59) and a-o-apio-L-furanosyl-1-phosphate (60) and their cyclic phosphates were separated by chromatography and identified by H n.m.r. o-Apiose is metabolized in parsley and Lemna minor with the possible formation of UDP-D-apiose. L. minor will convert UDP-a-glucuronic acid into a-o-apio-D-furanosyl-1,2-cyclic phosphate (61) but no evidence of UDP-o-apiose was found, although it is possible that (61) arose from the rapid hydrolysis of UDP-o-apiose. 

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. 

Preparations from various sources show closely similar properties, e. g., nitrogen 3-3.5%, D-glucosamine 30-40%, D-glucuronic acid 40-45%, acetyl 8-12%, [o]d —60 to —70° in water. 

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. 

The simultaneous protection of two hydroxyl groups by condensation of sugars with carbonyl compounds to give 1,3-dioxolanes or 1,3-dioxanes is also applicable to D-glucuronic acid. Principally, for the preparation of O-alkylidene-a-D-glucofuranuronic acid derivatives, two methods are available 1, direct condensation of 2 or 4 with... 

In a laboratory study by Schlekat et al. [15], it was demonstrated that coating silica particles with an exopolymer prepared from an estuarine bacterium enhanced the sorption of cadmium on to the particles. The composition of the exopolymer was glucose, galactose and glucuronic acid in the ratio 5 2 1. These investigations also compared the effects of salinity, pH and different concentrations of cadmium. Increasing salinity resulted in less cadmium associated with the particles, presumably due to competition with the chloride ion. The pH had a dramatic effect, resulting in only ca. 10% absorbed at pH 5 to more than 95% at pH 9. 

By the route shown in Scheme 7, 5-amino-5,6-dideoxy-DL-gulonic acid (dl-69) was prepared.113 When D-glucuronic acid reacted with l-glutamic acid under reductive conditions, 6-deoxy-6-[l,3-di(carboxy-propyl)amino]-L-gulonic acid was formed.114... 

With washed microsomal preparations from the liver of guinea pig, rat, rabbit, mouse, and cat, conjugation of bilirubin also occurred at appreciable rates in the absence of added bivalent cation (P3). With digitonin-activated preparations from rat liver, glycosyl transfer rates were, respectively, 16-33%, 0-38%, and 58-78% of the values found at nearsaturation of Mg + when UDP-glucuronic acid, UDP-xylose, or UDP-glucose were assayed (F3, HIO). The great variability of the rates could point to an artifact. 

With UDP-glucuronic acid as the variable substrate and bilirubin at constant concentration, Michaelis-Menten kinetics were obeyed (A2, H2, HIO, P5, V2, W12). Rat liver microsomal preparations treated in different ways yielded apparent Km for UDP-glucuronic acid of 0.37-0.70 mM (A2, H2, HIO, V2), with albumin-bound bilirubin as the aglycon a higher value (1.66 mAf) was found in a carrier-free system (W12). These values probably do not represent Km for UDP-glucuronic acid at saturation with bilirubin (P5, V6). Under certain conditions of activation, cell extracts from livers of newborn and adult rats, wdicn tested with o-amino-... 

F5. Fevery, J., Leroy, P., Van De Vijver, M., and Heirwegh, K. P. M., Structures of bilirubin conjugates synthesized in vitro from bilirubin and uridine diphosphate glucuronic acid, uridine diphosphate glucose or uridine diphosphate xylose by preparations from rat liver. Biochem. J. 129, 635-644 (1972). 

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