title: Reversible acetonitrile-induced inactivation/activation of thermolysin.
abstract: Thermolysin is catalytically inactive in mixtures of 10-15 % 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.
authors.affiliation: Department of Chemistry The Edinburgh Centre for Protein Technology The University of Edinburgh King's Buildings, West Mains Road Edinburgh EH9 3JJ, UK.
authors.forename: Rein V
authors.initials: RV
authors.lastname: Ulijn
authors.forename: Anja E M
authors.initials: AE
authors.lastname: Janssen
authors.forename: Barry D
authors.initials: BD
authors.lastname: Moore
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Halling
authors.forename: Sharon M
authors.initials: SM
authors.lastname: Kelly
authors.forename: Nicholas C
authors.initials: NC
authors.lastname: Price
mesh_terms: D000097:Acetonitriles / Q000494:pharmacology*; D002384:Catalysis; D004789:Enzyme Activation / Q000187:drug effects; D007700:Kinetics; D012997:Solvents / Q000494:pharmacology; D013820:Thermolysin / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism
chemical_list: D000097:Acetonitriles; D012997:Solvents; D013820:Thermolysin; C032159:acetonitrile