Phosphoglucomutase and

Leloir110(a) has described a conversion of D-mannosyl phosphate to D-mannose 6-phosphate by phosphoglucomutase, and here, too, the reaction requires catalytic quantities of a-D-glucose 1,6-diphosphate. The role of the latter is probably to generate a-D-mannose 1,6-diphosphate as follows. 

Hall, M. A., and L. Ordin. Subcellular location of phosphoglucomutase and UDP glucose pyrophosphorylase in avena coleoptiles. Physiol. Plant. 20 624-633, I%7. 

Ray, W.J., Jr. and C.B. Post. 1990. The oxyvanadium constellation in transition-state-analogue complexes of phosphoglucomutase and ribonuclease. Structural deductions from electron-transfer spectra. J. Biochem. 29 2779-2789. 

Figure 15-3 Coupled enzyme assay to determine glycogen phosphorylase activity. As long as the activity of phosphoglucomutase and glucose-6-phosphate dehydrogenase are not rate-limiting, the AA340/At is directly proportional to the A[glucose-l -phosphate]/Atime.

The involvement of methionine sulfonium salts in these chemical cleavage reactions may stimulate experiments to show the significance of special methionine residues in the active centers and the catalytic sites of enzymes. Such an important role for a particular methionine has been postulated for the enzymes phosphoglucomutase and chymotrypsin on the basis of photooxidation studies (Ray et al., 1960). 

The effect of 03 on plant metabolism is complex, and contradictory results have been reported. However, it is well established that photochemical oxidants such as 03 and PAN can oxidize SH groups, and such oxidation may be sufficient to cause loss of enzyme activity. For example, several enzymes involved in carbohydrate metabolism, such as phosphoglucomutase and... 

The biosynthesis of glycogen occurs from glucose-6-phosphate. As indicated earlier, this is one of several alternative fates of glucose-6-phosphate in addition to glycolysis. Glucose-6-phosphate via phosphoglucomutase and glucose-1,6-bisphosphate can be reversibly... 

Many enzymes are dependent on dissociable metal ions for their activity, and the operation of most of the important metabolic systems thus requires the presence of these cofactors. For example, the list of enzymes requiring Mg is a long one and includes the oxidases and decarboxylases for the keto acids, most of the enzymes involved in phosphate metabolism, some dehydrogenases, some peptidases, phosphoglucomutase and enolase. These enzymes may be inhibited with inhibitors forming stable complexes with Mg ions. For example, malonate and other dicarboxylic compounds are able to chelate effectively with Mg" and other metal ions, and their inhibition may result from the reduction of metal ion concentration in the medium or the removal of the metal ions from the enzyme [3] ... 

Mesak, L.R. Dahl, M.K. Purification and enzymatic characterization of PgcM A /1-phosphoglucomutase and glucose-1-phosphate phosphodismutase of Bacillus subtilis. Arch. Microbiol., 174, 256-264 (2000)... 

Glucose-l-P04 is converted to glucose-6-P04 by the enzyme phosphoglucomutase, and can be dephosphorylated in the liver to enter the blood stream for distribution. In muscle cells, it goes directly into glycolysis. 

---