Purification and Properties of ³-GIutamyltranspeptidase from Bacillus suhtilis (natto)

Abstract

To understand the mechanism by which ³-polyglutamic acid (³-PGA) in the sticky material of natto was synthesized, we purified the ³-glutamyltranspeptidase (³-GTP) (EC 2.3.2.2) from the culture broth of Bacillus subtilis (natto) to homogeneity. ³-GTP was composed of two subunits with molecular weight of 45,000 and 22,000. The N-terminal amino acid sequence of light subunit was homologous with that of ³-GTP from Escherichia coli. The optimum pH and temperature of activity were 8.5 and 60°C. The enzyme was inactivated by incubation for 15 min at pH 8.0 and 55°C, but little loss of the activity was detected at 40°C. ³-GTP used glutamine as a ³-glutamyl donor and acceptor for ³-PGA synthesis. Dipeptides were etter ³-glutamyl acceptors than free amino acids. © 1991, Japan Society for Bioscience, Biotechnology, and Agrochemistry. All rights reserved.