Of melibiose

In bacteria and yeasts, Li+ has strain-dependent, inhibitory, and morphological effects upon growth. The driving force behind the transport of carbohydrates and amino acids in bacteria is the proton gradient, and in both E. coli [228] and Salmonella typhimurium cells [229], Li+ stimulates the movement of proline into cells via a Li+/proline symport and the transport of melibiose via a cotransport pathway [230]. In both cases, Li+ is replacing Na+ and results in the inhibition of growth. 

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. 

Synthesis of melibiose Isolation of manninotriose, stachyose (manneotetrose) from ash manna correct molecular formula for Fischer 1902 13... 

Rate of Hydrolysis of Phenyl a-D-Galactopyranoside and of Melibiose, by Different... 

Source of enzyme Ratio of rate of hydrolysis of melibiose to that of phenyl a-D-galactopyranoside... 

Melibiose occurs in Nature primarily as a constituent of the trisaccharide raffinose, although it has been identified in such plant exudates as ash manna and an exudate from mallow. Historical details of the discovery and preparation of melibiose have been reviewed by Harding68 and will not be reiterated here. Modern methods for the preparation of melibiose have been recorded by Hudson and Harding60 and by Bates and associates.66 Melibiose can be purchased from a number of chemical-supply firms. 

In 1951, Whistler and Durso reported68 the isolation of epimelibiose by partial, acid hydrolysis of the polysaccharide guaran, followed by charcoal-column fractionation of the products. ThA material was obtained in anhydrous crystalline form from a mixture of methyl and butyl alcohols it had m.p. 201°, [a]26D + 120.9° — +124.6° in 36 hr. (c 2, in water). The yield was 2.2% of the weight of guaran used. Epimelibiose has also been produced72" in crystalline form following the ammonia-catalyzed alkaline isomerization of melibiose. 

The structure of epimelibiose was established58 through periodate oxidation, and by comparison of its osazone with that of melibiose (melting point, mixed melting point, and x-ray diffraction pattern). 

That a-galactosidases are different from /3-galactosidases is shown by the difference in their behavior on precipitation with tannin (or alcohol), adsorption, and inactivation. " Among themselves, the various a-galactosidases are similar in the effect of pH, but they can be differentiated by virtue of their hydrolytic action on various substrates, for example, through the ratio of the rate of hydrolysis of melibiose to the rate of hydrolysis of phenyl /3-D-galactoside (see Table XIII, specificity). ... 

Comparison of Hydrolysis of Melibiose and Phenyl a-T>-Oalactoside with a-Galoctosidoses from Various Sources ... 

Fletcher and Diehl, in studying the preparation of melibiose from raffinose by the fermentative hydrolysis of the trisaccharide, noticed a new form of the disaccharide. By observing the mutarotation of the new form, and by comparing the infrared spectra with that of an authentic... 

Note the various ways in which the a anomeric linkage is designated in the different types of structures. Realizing the structure of melibiose we can deduce compounds A and B and their related products. 

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