Reversible acetonitrile-induced inactivation/activation of thermolysin

R.V. Ulijn, A.E.M. Janssen, B.D. Moore, P.J. Halling, S.M. Kelly, N.C. Price

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)


Thermolysin is catalytically inactive in mixtures or 70-15% acetonitrile in aqueous buffer. Unexpectedly, dilution of the inactive enzyme with acetonitrile leads to complete recovery of the catalytic activity in a similar way to dilution with aqueous buffer. Circular dichroism and fluorescence studies of thermolysin in the same solvent mixtures reveal discontinuous changes in the overall secondary and tertiary protein structure that correlate well with the reversible differences in catalytic activity. The spectra on either side of the minimum activity point are different from each other, a fact indicating that the enzyme may be able to access two active conformations which are thermodynamically stable in different solvent environments.
Original languageEnglish
Pages (from-to)1112-1116
Number of pages4
Issue number11
Publication statusPublished - 4 Nov 2002


  • activity studies
  • biocatalysis
  • enzymes
  • protein structures
  • solvent effects
  • Aqueous-organic media
  • alpha-chymotrypsin
  • catalytic activity
  • solvents
  • fluorescence
  • denaturation
  • mixtures
  • relevant


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