Bacterial gamma-glutamyltranspeptidases: comparison of Escherichia coli and Pseudomonas gamma-glutamyltranspeptidase.

A high-level expression system for the Escherichia coli HB101 gamma-glutamyltranspeptidase (GGT) gene was constructed to obtain a sufficient amount of the enzyme for structural studies. About 300 mg of the enzyme was purified from 2 1 of culture broth. Both subunits were needed to reconstitute GGT activity. The E. coli GGT and the Pseudomonas GGT were compared with respect to catalytic properties and immunological relationships. Both enzymes showed different acceptor specificities. Relatively high immunocross-reactivity was observed between the small subunits of both enzymes by Western blot analysis using antibodies prepared against either enzyme.