I. The Use of Numerical Methods in the Treatment of Data from Enzyme Kinetics Studies. II. The Effect of Enzyme Concentration on the Rate of a Reaction Catalyzed by Alpha-Chymotrypsin

Citation

Booman, Keith Albert (1956) I. The Use of Numerical Methods in the Treatment of Data from Enzyme Kinetics Studies. II. The Effect of Enzyme Concentration on the Rate of a Reaction Catalyzed by Alpha-Chymotrypsin. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/6602-GW22. https://resolver.caltech.edu/CaltechETD:etd-03182004-144601

Abstract

Three methods have been developed for handling data from enzyme kinetics studies. The first method, which involves the use of Simpson's rule, is applicable when Michaelis-Menten (21) kinetics obtain and has the advantage of a short calculation time. The second method, which involves approximation of the data by a set of orthogonal polynomials, is applicable when the reaction mechanism is either unknown or so complicated that the mathematical formulation is intractable. The third method applies when the Michaelis-Menten mechanism holds but the steady state approximation is invalid. Use is made of Simpson's rule and of numerical differentiation. The effect of enzyme concentration in the alpha-chymotrypsin catalyzed hydrolysis of L-tryptophanhydroxamide has been studied. All the work was done at 25[degrees]C. at an ionic strength of either 0.15 M. or 0.30 M. The experiments covered the pH range of 6 to 8. The buffer from pH 6 to pH 7 was cacodylic acid. The buffer used at pH 8 was tris-(hydroxymethyl)-aminomethane. It is shown that the effect of changing enzyme concentration is understandable in terms of a reversible dimerization of the enzyme which makes one active site of the two enzyme molecules involved unavailable for bonding to substrate. This effect decreases with increasing pH, becoming negligible at pH 8.

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