Purification and properties of an extracellular leucine aminopeptidase from the Bacillus sp. N2

A halophilic bacterium was isolated from fermented anchovy sauce and identified as Bacillus species. An extracellular leucine aminopeptidase from Bacillus sp. N2 was purified to homogeneity using four successive purification steps. The enzyme has a native molecular mass of about 57000 Da using FPLC...

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Bibliographic Details
Published in:Journal of applied microbiology 1998-09, Vol.85 (3), p.561-566
Main Authors: Lee, G.D, Chun, S.S, Kho, Y.H, Chun, H.K
Format: Article
Language:English
Subjects:
Bacillus
Biological and medical sciences
Biological Sciences
Biology of microorganisms of confirmed or potential industrial interest
Biotechnology
food microbiology
food processing
Fundamental and applied biological sciences. Psychology
Miscellaneous
Mission oriented research
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Summary:A halophilic bacterium was isolated from fermented anchovy sauce and identified as Bacillus species. An extracellular leucine aminopeptidase from Bacillus sp. N2 was purified to homogeneity using four successive purification steps. The enzyme has a native molecular mass of about 57000 Da using FPLC gel filtration analysis and a molecular mass of 58000 Da using SDS-polyacrylamide gel electrophoresis. This monomeric leucine aminopeptidase showed maximum enzyme activity at pH 9(.)5. The optimum temperature was 50 degrees C when L-Leu-p-nitroanilide was the substrate. The leucine aminopeptidase was inactivated by 1,10-phenanthroline, dithiothreitol and sodium dodecyl sulphate. Enzyme activity was increased by addition of Co2+. It is likely that Co2+ plays an important role in the catalysis or stability of the Bacillus sp. N2 leucine aminopeptidase. Sodium chloride (0-4(.)5 mol l-1) increased the hydrolytic activity towards L-Leu-p-nitroanilide. The N-terminal amino acid sequence was Glu-Arg-Glu-Leu-Pro-Phe-Lys-Ala-Lys-His-Ala-Tyr-Ser-Thr-Ile. The purified enzyme had a high specificity for L-Leu-p-nitroanilide.
ISSN:1364-5072
1365-2672
DOI:10.1046/j.1365-2672.1998.853536.x