Affiliation:
1. Department of Microbiology, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands
Abstract
A tripeptidase from a cell extract of
Lactococcus lactis
subsp.
cremoris
Wg2 has been purified to homogeneity by DEAE-Sephacel and phenyl-Sepharose chromatography followed by gel filtration over a Sephadex G-100 SF column and a high-performance liquid chromatography TSK G3000 SW column. The enzyme appears to be a dimer with a molecular weight of between 103,000 and 105,000 and is composed of two identical subunits each with a molecular weight of about 52,000. The tripeptidase is capable of hydrolyzing only tripeptides. The enzyme activity is optimal at pH 7.5 and at 55°C. EDTA inhibits the activity, and this can be reactivated with Zn
2+
, Mn
2+
, and partially with Co
2+
. The reducing agents dithiothreitol and β-mercaptoethanol and the divalent cation Cu
2+
inhibit tripeptidase activity. Kinetic studies indicate that the peptidase hydrolyzes leucyl-leucyl-leucine with a
K
m
of 0.15 mM and a
V
max
of 151 μmol/min per mg of protein.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
74 articles.
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