PURIFICATION AND PROPERTIES OF OXALOACETATE DECARBOXYLASE FROM CORYNEBACTERIUM-GLUTAMICUM

Oxaloacetate (OAA) decarboxylase (E.C. 4.1.1.3) was isolated from Cory nebacterium glutamicum. In five steps the enzyme was purified 300-fold to apparent homogeneity. The molecular mass estimated by gel filtrati on was 118 +/- 6 kDa. SDS-PAGE showed a single subunit of 31.7 KDa, in dicating an alpha(4) subunit structure for the native enzyme. The enzy me catalyzed the decarboxylation of OAA to pyruvate and CO2, but no ot her alpha-ketoacids were used as substrate. The cation Mn2+ was requir ed for full activity, but could be substituted by Mg2+, Co2+, Ni2+ and Ca2+. Monovalent ions like Na+, K+ or NH4+ were not required for acti vity. The enzyme was inhibited by CU2+, Zn2+, ADP, coenzyme A and succ inate. Avidin did not inhibit the enzyme activity, indicating that bio tin is not involved in decarboxylation of OAA. Analysis of the kinetic properties revealed a K-m for OAA of 2.1 mM and a K-m of 1.2 mM for M n2+. The V-max was 158 mu mol of OAA converted per min per mg of prote in, which corresponds to an apparent k(cat) of 311 s(-1).