A-D -Galactose

StmcturaHy, guar gum comprises a straight chain of D-mannose with a D-galactose side chain on approximately every other mannose unit the ratio of mannose to galactose is 2 1 (53). Guar gum has a molecular weight on the order of 220,000 (54). 

P-D-mannan with single 6-Unked a-D-galactose branches g 4)-p -D-glucomannan ... 

Recently Cavaleiro et al. described an easy synthetic approach to glycoporphyrins from zinc(n) protoporphyrin-IX dimethyl ester 4 and O-allyl carbohydrate acetonides 5A-E (D-ribose (A), D-galactose (B), D-glucose (C), and two isomeric derivatives (D) and (E) of D-fructose) by cross-metathesis (Scheme 2).12 Two equivalents of each carbohydrate and the Grubbs catalyst were used, giving the carbohydrate derivatives 6 in a range of 74% to 93% yields. 

This enzyme [EC 2.7.7.10], also known as UTP hexose-1-phosphate uridylyltransferase, catalyzes the reaction of UTP with a-D-galactose 1-phosphate to produce UDP-galactose and pyrophosphate (or, diphosphate), a-o-Glucose 1-phosphate can also function as a substrate, albeit not as effectively. 

This enzyme [EC 3.2.1.22] catalyzes the hydrolysis of melibiose to yield galactose and glucose. It will also act on terminal, nonreducing a-D-galactose residues in a-D-galactosides. In addition, it will hydrolyze a-D-fucosides. 

This enzyme [EC 2.4.1.56] catalyzes the reaction of UDP-A-acetyl-D-glucosamine with a lipopolysaccharide to produce UDP and an A-acetyl-D-glucosaminyl-lipopoly-saccharide. Thus, this enzyme transfers A-acetylgluco-saminyl residues to a D-galactose residue in the partially completed lipopolysaccharide core. 

The properties of disaccharides aren t a simple combination of the properties of the two monosaccharides present. For example, the disaccharide lactose (milk sugar) is a reducing sugar containing a (3-D-glucose linked to a D-galactose molecule. 

In our first measurements with solutions of 0.5 M a-D-galactose in 0.5 M boric acid, the constants of the mutarotation and of the change in the conductivity agreed very well. 

The aldohexoses have not been extensively studied by X-ray crystal-lographers. Crystals of a- and jS-D-galactose were examined by Sheldrick,21 who gave directions for crystallizing both anomers. In one preparation, the crystals of a-D-galactose were small plates large prismatic crystals of jS-D-galactose were also obtained. 

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