Ethyl galactoside

For over 40 years synthetic action of /3-galactosidases has also been known. Bourquelot and associates showed that 3-galactosidase from various sources could synthesize such compounds as ethyl galactoside from the free sugar and ethanol when the substrates were present in high concentrations (I). The equilibrium of the reaction is reached in spite of technical difficulties, such as inactivation of the enzyme and formation of condensation products of galactose with itself. 

The Rf values of two unknown compounds found in plain yogurt were identical to those of 7a-hydroxyriboflavin (Rf values 0.32 and 0.21) and riboflavin-p-galactoside (Rf values 0.14 and 0.10), but not to those of other flavin compounds [flavin adenine dinucleotide or FAD (Rf values 0 and 0), flavine mononucleotide or FMN (Rf values 0 and 0.05), 10-hydroxyethylflavin (Rf values 0.71 and 0.40), riboflavin (Rf values 0.55 and 0.32), and 10-formylmethylflavin (7 f values 0.86 and 0.76)] by TLC on silica gel with chloroform-methanol-ethyl acetate (5 5 2) and 1-butanol-benzyl alcohol-glacial acetic acid (8 4 3) as solvents, respectively. -" ... 

Mg " decreased trifluoroethyl galactoside by 10 -fold but for ethyl gal-actoside by 10 -fold. If the same substituted ethanols used as leaving groups were also used to intercept the galactosyl-enzyme, a value of jSjmc of —0.19 0.10 was obtained.Combination of this value with the jSig value gave a jSeq value of —0.56 0.05 for the equilibrium of eqn. (5.50) ... 

Galactoside hem then deca hydrate C jH2SC10125HH20. primulin. Bronze metallic needles or prisms from methanol + HCl. Bluish-violet by transmitted light. Very sol in methanol, ethanol, cold water forming deep red oln slightly sol in acetone practically insol in ethyl acetate. 

Draw the structural formula for ethyl a-D-galactopy-ranoside (ethyl a-D-galactoside). Label the anomeric carbon and the glycosidic bond. (See Example 17.4)... 

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