Synthesis of γ-Glutamyl-DOPA From L-Glutamine and l-DOPA by γ-Glutamyltranspeptidase of Escherichia coli K-12

Abstract

An E. coli strain, SH209, harboring pLC9-12 exhibited 5- to 6-fold higher γ-glutamyltranspeptidase activity than the wild-type strain, at each growth temperature tested. Maximum activity was observed at 20~25°C, as was observed with the wild type. A homogeneous enzyme preparation was obtained from the periplasmic fraction of the strain by a simple three-step method. The conditions for γ-glutamyl-DOPA synthesis from l-glutamine and l-DOPA were investigated using the enzyme preparation. Under the best conditions, the maximal yield of 79%, equivalent to 158 mM (51.5 g/l) of γ-glutamyl-DOPA as to both substrates, was obtained. γ-Glutamyl-DOPA was isolated from the reaction mixture and identified using an amino acid analyzer after hydrolysis with HCl or γ-glutamyltranspeptidase. © 1988, Japan Society for Bioscience, Biotechnology, and Agrochemistry. All rights reserved.