Purification and properties of diaminopimelate decarboxylase of Micrococcus glutamicus

Abstract

Diaminopimelate decarboxylase (EC 4.1.1.20) of Micrococcus glutamicus ATCC 13059 was purified to homogeneity. The enzyme had an apparent molecular weight of 191,000 as determined by gel filtration on Sephadex G-200. At protein concentrations of 20 and 10 μg per ml and in the absence of pyridoxal-5'-phosphate, it dissociated into a species of molecular weight 94,000. The polypeptide chain molecular weight as determined by sodium dodecyl sulphate Polyacrylamide gel electrophoresis was 100,000. The K_m formeso diaminopimelate was 0.5 mM and that for pyridoxal-5'-phosphate was 0.6 μM. Sulphydryl groups and pyridoxal-5'-phosphate were essential for activity and stability. The enzyme was inhibited significantly by L-lysine and DL-aspartic β-semialdehyde.