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The unique stability of Vibrio proteolyticus neutral protease under alkaline conditions affords a selective step for purification and use in amino acid-coupling reactions.

Authors
  • Durham, D R
Type
Published Article
Journal
Applied and environmental microbiology
Publication Date
Aug 01, 1990
Volume
56
Issue
8
Pages
2277–2281
Identifiers
PMID: 2403247
Source
Medline
License
Unknown

Abstract

A procedure is described for the purification of a neutral protease from fermentation broths of Vibrio proteolyticus. The key feature of the purification scheme is the selective, irreversible inactivation of a contaminating exoenzyme, aminopeptidase, by alkali treatment, rather than removal of this enzyme by conventional chromatographic methods. Fermentation broths or concentrates were brought to pH 11.5 to 11.7 by Na2CO3-NaOH addition and incubated at 25 degrees C until aminopeptidase activity was diminished. The alkali treatment resulted in greater than 99% reduction of aminopeptidase activity with minimal loss of neutral protease activity. The neutral protease could be further purified to apparent homogeneity by QA-52 cellulose chromatography. The alkali treatment of fermentation concentrates was also useful for preparation of V. proteolyticus neutral protease to effect the coupling of N-protected aspartic acid and phenylalanine methyl ester for the production of N-aspartylphenylalanine methyl ester, a precursor for the sweetener aspartame.

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