Reaction
The method by which sucrose phosphorylase converts sucrose to D-fructose and alpha-D-glucose-1-phosphate has been studied in great detail. In the reaction, sucrose binds to the enzyme, at which point fructose is released by the enzyme-substrate complex. A covalent glucose-enzyme complex results, with beta-linkage between an oxygen atom in the carboxyl group of an aspartyl residue and C-1 of glucose. The covalent complex was experimentally isolated by chemical modification of the protein using NaIO4 after addition of the substrate (Voet and Abeles, 1970; Mirza et al. 2006), supporting the hypothesis that reaction catalyzed by sucrose phosphorylase proceeds through the ping-pong mechanism. In the final enzymatic step, the glycosidic bond is cleaved through reaction with a phosphate group, yielding α-D-glucose-1-phosphate.
In a separate reaction, α-D-glucose-1-phosphate is converted to glucose-6-phosphate by the action of phosphoglucomutase (Tedokon et al. 1992). Glucose-6-phosphate is an extremely important intermediate for several pathways in the human body, including glycolysis, gluconeogenesis, and the pentose phosphate pathway (Nelson and Cox 2005). The function of sucrose phosphorylase is especially significant due to the role α-D-glucose-1-phosphate in energy metabolism.
Read more about this topic: Sucrose Phosphorylase
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