Remarkable activation of enzymes in nonaqueous media by denaturing organic cosolvents
- Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Chemistry
The rates of transesterification reactions catalyzed by the protease subtilisin Carlsberg suspended in various anhydrous solvents at 30 C can be increased more than 100-fold by the addition of denaturing organic cosolvents (dimethyl sulfoxide or formamide); in water, the same cosolvents exert no enzyme activation. At 4 C, the activation effect on the lyophilized protease is even higher, reaching 1,000-fold. Marked enhancement of enzymatic activity in anhydrous solvents by formamide is also observed for two other enzymes, {alpha}-chymotrypsin and Rhizomucor miehei lipase, and is manifested in two transesterification reactions. In addition to lyophilized subtilisin, crosslinked crystals of subtilisin are also amenable to the dramatic activation by the denaturing cosolvents. In contrast, subtilisin solubilized in anhydrous media by covalent modification with poly(ethylene glycol) exhibits only modest activation. These observations are rationalized in terms of a mechanistic hypothesis based on an enhanced protein flexibility in anhydrous milieu brought about by the denaturing organic cosolvents. The latter exert their lubricating effect largely at the interfaces between enzyme molecules in a solid preparation, thus easing the flexibility constraints imposed by protein-protein contacts.
- OSTI ID:
- 182894
- Journal Information:
- Biotechnology and Bioengineering, Journal Name: Biotechnology and Bioengineering Journal Issue: 1 Vol. 49; ISSN BIBIAU; ISSN 0006-3592
- Country of Publication:
- United States
- Language:
- English
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