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Purification and characterization of an aminopeptidase from Lactobacillus casei subsp. rhamnosus S93
Author(s) -
Arora G.,
BH Lee
Publication year - 1994
Publication title -
biotechnology and applied biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.468
H-Index - 70
eISSN - 1470-8744
pISSN - 0885-4513
DOI - 10.1111/j.1470-8744.1994.tb00293.x
Subject(s) - aminopeptidase , lactobacillus casei , enzyme , leucyl aminopeptidase , lysis , enzyme assay , biochemistry , leucine , lactobacillus rhamnosus , biology , hydrolysis , amino acid , lactobacillus , chemistry , chromatography , fermentation
An aminopeptidase of broad specificity was extracted by cell lysis of a selected strain of Lactobacillus casei subsp. rhamnosus during the late exponential phase. The enzyme was purified 195‐fold from crude extract by using an f.p.l.c. system. Native and SDS/PAGE of the purified enzyme showed a single protein band of 89 kDa. The maximum aminopeptidase activity was observed at pH 7.0 and 39 degrees C. The enzyme hydrolysed a range of nitroanilide‐substituted amino acids, as well as dipeptides, and accounted for most of the aminopeptidase activity found in cell‐free extracts. The enzyme activity was inhibited by metal chelators such as EDTA and 1,10‐phenanthroline. Cobalt ions only stimulated aminopeptidase activity and were also able to re‐activate the enzyme previously inhibited by metal chelators. The Km and Vmax. values of the aminopeptidase for leucine p‐nitroanilide were 0.06 mM and 12.6 mmol/min per mg of protein respectively. This enzyme was stable over the pH range of 5‐9 and below 45 degrees C.