Purification and properties of glucosaminephosphate isomerase of Proteus mirabilis.

A glucosamine-P isomerase has been identified in Proteus mirabilis. The 113-fold purified enzyme exhibits a pH optimum of 7.5 with a secondary maximum at 8.5 and a temperature optimum at 37 degrees C. The apparent Km was 13.3 mM for fructose-6-P and 18.8 mM for L-glutamine. Molecular weight of the enzyme has been estimated as 120 000 and the protein can be dissociated in four subunits by SDS-polyacrylamide electrophoresis.