A-glucose 1-phosphate

Phospholylases, as summarized in Table 28.1, catalyze the reversible phospho-rolysis of polysaccharides or oligosaccharides, and produce phosphorylated mono-saccharides. Among such enzymes a-glucan phosphorylase (GP, EC 2.4.1.1), sucrose phosphorylase (SP, EC 2.4.1.7) and cellobiose phosphorylase (CBP, EC 2.4.1.20) are of great interest, since they can produce a-glucose 1-phosphate (a-GlP) from three major biomasses starch, sucrose, and cellulose. Only these three are described in this paper, a comprehensive review of other phosphorylases can be found in Kitaoka and Hayashi (2002). 

Recently, a glucose 1-phosphate thymidyltransferase from Salmonella enterica (strain LT2) has been characterized following expression of the gene... 

In the presence of a-lactalbumin, however, only glucose and cellobiose (Glc)3l-4Glc) [37] are the preferred acceptors. Neither o-mannose, D-allose, D-galactose, o-ribose, nor D-xylose are substrates. Glucuronic acid and a-glucose-1-phosphate (monosaccharides with a negative charge) are also not accepted. 

II. 91%. A normal constituent of resting muscle, probably always existing in equilibrium with fructose-6-phosphate. For the enzymatic conversion from the I -phosphate see a -Glucose-1 -phosphate. Isoln from a crude mixture of hex -ose phosphates, obtained by yeast fermentation Robison, King, -Biochem. J. 25, 323 (1931). Prepn by the action of phosphoglucomutase on a-glucose-1 -phosphate Colowjck. Sutherland, J. Biol Chem. 144, 423 (1942) from acetone... 

A-glucose 1-phosphate sugar phosphate found widely in plants, where it is the precursor of starch. 

The monomer unit for the bios mthesis of starch is D-glucose in the pyranose form. The monomer needs to be activated. First a glucose-1-phosphate is converted into ADP-glucose catalyzed by glucose-1-phosphate adenylyltransferase ... 

To explain these reactions it must be postulated that a glucosyl-enzyme is formed as intermediate. Since in the initial reaction a-glucose-1-phosphate (and not the /3 compound) is formed the mechanism must involve two consecutive double displacements. Thus, the combining group in the enzyme being postulated to be an oxygen function, and R—OH = fructose, the mechanism can be depicted thus ... 

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