A-Galactose

Oxidation of galactose (or a galactose-containing sugar) to mucic acid. Dissolve 1 g. of galactose or lactose in a mixture of 10 ml. of water and 5 ml. of concentrated nitric acid contained in a small evaporating dish, and evaporate the solution to dryness on a water bath. Stir the cold residue with 10 ml. of cold water, filter off the mucic acid, wash it with cold water, dry and determine the m.p. (212-213° with decomposition). 

Figure 20-6. Pathway of conversion of (A) galactose to glucose in the liver and (B) glucose to lactose in the lactating mammary gland.

The six-carbon sugar a-galactose is identical to a-glucose except at carbon atom number 4, where the orientations are different. Draw the molecular structure of a-galactose. Simplify the stmcture by using flat rings rather than the true three-dimensional forms. 

An illustrative example of carbohydrate-protein recognition has been reported by Chen and coworkers [192] using a C18-mucin mimic polymer that interacts hydro-phobically with SWCNTs. This biohybrid is able to specifically recognize the lectin Hdixpomatia agglutinin (Figure 1.15 A). Galactose-modified CNTs are able to capture... 

If branching is (1 —> 3), no glycol grouping will be present in any central unit and it may be seen that reaction will only occur on the terminal units. Such is the case with the polysaccharide laminarin, with the glucan of yeast membrane, and with a galactose-containing polysaccharide isolated from agar.146-148... 

Synthesis of glycoside 138, a galactose conjugate of SIN-1 13, has been achieved and its role as /3-galactosidase-mediated nitric oxide donor has been evaluated <2005JOC3518>. 

There is no glycemic response to glucagon or epinephrine (Fig. 42-1), whereas a galactose load causes a normal glycemic response. Forearm ischemic exercise produces a blunted venous lactate rise or no response. Serum CK activity is variably, often markedly, increased. The ECG shows left ventricular or biventricular hypertrophy in most patients, and the EMG may show myopathic features alone or associated with fibrillations, positive sharp waves and myotonic discharges. This mixed EMG pattern in patients with weakness and distal wasting often reinforces... 

The great majority of untreated galactosemic subjects who survive more than a few weeks develop lenticular cataracts. These first appear as a faint milkiness of the anterior capsule of the lens between the fourth and eighth week. Opacity of the lens increases rapidly unless the infant is fed a galactose-free diet. On such a diet, early cataracts regress but rarely vanish completely, though in the best cases vision is little affected (B16, B19, H10, K13, W4). If treatment has been delayed and, in consequence,... 

The mucic acid test is now only of historical interest. It depends on the oxidation of galactose or saccharides containing a galactose residue, such as lactose, with nitric acid to yield mucic acid. Mucic acid is highly insoluble in water, while the isomeric dicarboxylic acids yielded by other sugars are soluble. Mucic acid may be identified by its characteristic thallium salt. 

L2. Leloir, L. F., The enzymatic transformation of uridine diphosphate glucose into a galactose derivative. Arch. Biochem. Biophys. 33, 186-190 (1951). 

Guan, L., Sahin-Toth, M. and Kaback, H. R. (2002). Changing the lactose permease of Escherichia coli into a galactose-specific symporter, Proc. Natl Acad. Sci. USA, 99, 6613-6618. 

Fig. 8.—Composition of the Core Oligosaccharide from a Galactose-epimeraseless mutant38 of Salmonella typhimurium,S7...

The influence of -lactose on the growth of crystals of a-lactose has recently been analyzed by Visser and Bennema (68). The a- and (3-lactoses 4a and 4b are disaccharides composed of a galactose and an a- or (3-glucose moiety linked... 

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