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Summary: Proc. Natl. Acad. Sci. USA
Vol. 95, pp. 1280912813, October 1998
Biochemistry
Directed evolution of a thermostable esterase
LORI GIVER, ANNE GERSHENSON, PER-OLA FRESKGARD*, AND FRANCES H. ARNOLD
Division of Chemistry and Chemical Engineering, Mail Code 210-41, California Institute of Technology, Pasadena, CA 91125
Edited by Norman R. Pace, University of California, Berkeley, CA, and approved September 5, 1998 (received for review April 30, 1998)
ABSTRACT We have used in vitro evolution to probe the
relationship between stability and activity in a mesophilic
esterase. Previous studies of these properties in homologous
enzymes evolved for function at different temperatures have
suggested that stability at high temperatures is incompatible
with high catalytic activity at low temperatures through
mutually exclusive demands on enzyme flexibility. Six gener-
ations of random mutagenesis, recombination, and screening
stabilized Bacillus subtilis p-nitrobenzyl esterase significantly
(>14°C increase in Tm) without compromising its catalytic
activity at lower temperatures. Furthermore, analysis of the
stabilities and activities of large numbers of random mutants
indicates that these properties are not inversely correlated.
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