Model
Digital Document
Publisher
Florida Atlantic University
Description
The effects of added salt on the deacylation rate constant of
trans-cinnamoylchymotrypsin were examined. Ionic strength effects on
the equilibrium constant of an ionizable, enzymic group of pKa 7.25
were also studied. Through the development of methods for the precise
measurement of pH and observed rate constants, very small changes
in the experimental parameters could be detected. It was found that
neither the deacylation rate constant nor the kinetically determined pKa exhibited a significant salt effect over the ionic strength range of 0.04
to 0.12 M. Based on the known three-dimensional structure of the
active site of chymotrypsin, four plausible mechanisms were considered
in light of the experimental absence of salt effects. The presence of calcium ion at low concentrations significantly perturbed
the values of the deacylation rate constant and the protonic equilibrium
constant.
trans-cinnamoylchymotrypsin were examined. Ionic strength effects on
the equilibrium constant of an ionizable, enzymic group of pKa 7.25
were also studied. Through the development of methods for the precise
measurement of pH and observed rate constants, very small changes
in the experimental parameters could be detected. It was found that
neither the deacylation rate constant nor the kinetically determined pKa exhibited a significant salt effect over the ionic strength range of 0.04
to 0.12 M. Based on the known three-dimensional structure of the
active site of chymotrypsin, four plausible mechanisms were considered
in light of the experimental absence of salt effects. The presence of calcium ion at low concentrations significantly perturbed
the values of the deacylation rate constant and the protonic equilibrium
constant.
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