<p>This model represents the beta-phosphoglucomutase enzyme which catalyses the interconversion of beta-D-glucose-1-phosphate and beta-D-glucose-6-phosphate. The 6-phosphate is capable of non-enzymatic anomerisation (alpha to beta or vice versa) while the 1-phosphate is not. A separate enzyme is responsible for the isomerisation of the alpha anomers. Beta-D-glucose-1-phosphate results from the phosphorolysis of maltose (<db_xref db="EC" dbkey="2.4.1.8"/>), trehalose (<db_xref db="EC" dbkey="2.4.1.64"/>) or trehalose-6-phosphate (<db_xref db="EC" dbkey="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.</p><p>Beta-phosphoglucomutase is a member of the haloacid dehalogenase superfamily of hydrolase enzymes. These enzymes are characterised by a series of three catalytic motifs positioned within an alpha-beta (Rossman) fold [<cite idref="PUB00003337"/>]. 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 [<cite idref="PUB00009589"/>, <cite idref="PUB00009540"/>]. 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. </p><p>The enzyme from <taxon tax_id="1358">Lactococcus lactis</taxon> has been extensively characterised including a remarkable crystal structure which traps the pentacoordinate transition state [<cite idref="PUB00014792"/>]. </p>