Effect of water activity on the rate profile of subtilisin Carlsberg in toluene in the presence of an organo-soluble acid- base buffer

N. Harper, M. Dolman, B.D. Moore, P.J. Halling

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The ionisation state of the enzyme and the water activity (alpha (w)) of the system are two important factors which affect catalytic activity in low-water organic solvents. Here we investigate the interaction between effects of alpha (w) and the ionisation state of subtilisin Carlsberg, controlled by an organo-soluble dendrimer buffer. It was shown that alpha (w) does not have a major effect on the relationship between rate of transesterification in toluene and buffer ratio, [sodium salt]/[acid]. The weak dependence on alpha (w) (between 0.54 and 0.85) probably reflects compensating effects on ionisation equilibria for the buffer and the carboxyl groups on the enzyme. (C) 2001 Elsevier Science Inc. All rights reserved.
Original languageEnglish
Pages (from-to)413-416
Number of pages3
JournalEnzyme and Microbial Technology
Issue number6-7
Publication statusPublished - 4 Oct 2001


  • subtilisin
  • organic solvents
  • ionisation state
  • water activity
  • buffer
  • Dendritic macromolecules
  • convergent approach
  • solvents
  • enzymes
  • state
  • media
  • ph
  • biocatalysis

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