ISSN:
0006-3592
Keywords:
enzymes
;
organic solvents
;
mechanism
;
subtilisin
;
microscopic rate constants
;
Chemistry
;
Biochemistry and Biotechnology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Process Engineering, Biotechnology, Nutrition Technology
Notes:
We report here the first determinations of individual rate constants and equilibrium constants for enzymatic reactions in essentially anhydrous organic solvents. Using the added nucleophile method we have measured the effect of changing solvent on the binding and catalytic steps for subtilisin-catalyzed transesterification of N-protected amino acid esters. The detailed information generated indicates that once the substrate has bound to the enzyme, the catalytic machinery can work at rates equivalent to those in water. The decreased overall rates for subtilisin suspended in anhydrous solvents are merely the result of extremely high values for Ks, in most cases, coupled with low concentrations of nucleophile (∼1.0M in organic solvents, and 55M in water). The method described, which is generally applicable, and straightforward experimentally, will, we believe, enable a clearer understanding of how changing solvent can predictably affect the activity and specificity of the enzyme. © 1992 John Wiley & Sons, Inc.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bit.260400910
