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beta-phosphoglucomutase This model represents the beta-phosphoglucomutase enzyme which catalyzes the interconverison of beta-D-glucose-1-phosphate and beta-D-glucose-6-phosphate. The 6-phosphate is capable of non-enzymatic anomerization (alpha <-> beta) while the 1-phosphate is not. A separate enzyme is responsible for the isomerization of the alpha anomers. Beta-D-glucose-1-phosphate results from the phosphorylysis of maltose (2.4.1.8), trehalose (2.4.1.64) or trehalose-6-phosphate (2.4.1.216). Alternatively, these reactions can be run in the synthetic direction to create the disaccharides. All sequenced genomes which contain a member of this family also appear to contain at least one putative maltose or trehalose phosphorylase. Three species, Lactococcus, Enterococcus and Neisseria appear to contain a pair of paralogous beta-PGM's. Beta-phosphoglucomutase is a member of the haloacid dehalogenase superfamily of hydrolase enzymes. These enzymes are characterized by a series of three catalytic motifs positioned within an alpha-beta (Rossman) fold. beta-PGM contains an inserted alpha helical domain in between the first and second conserved motifs and thus is a member of subfamily IA of the superfamily. The third catalytic motif comes in three variants, the third of which, containing a conserved DD or ED, is the only one found here as well as in several other related enzymes (TIGR01509). The enzyme from L. lactis has been extensively characterized including a remarkable crystal structure which traps the pentacoordinate transition state. [Energy metabolism, Biosynthesis and degradation of polysaccharides]
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