I. The Consequences of Systematic Error in Enzyme Kinetics. II. L-Tyrosyl-L-Tyrosine Derivatives for the Detection of Transpeptidation in α-Chymotrypsin-Catalyzed Hydrolyses. III. The Interaction of α-Methyl-α-Acylamino Acids with α-Chymotrypsin. IV. The Apparent Ionization Constants of a Series of Phenylalanine Derivatives

Citation

Almond, Harold Russell (1961) I. The Consequences of Systematic Error in Enzyme Kinetics. II. L-Tyrosyl-L-Tyrosine Derivatives for the Detection of Transpeptidation in α-Chymotrypsin-Catalyzed Hydrolyses. III. The Interaction of α-Methyl-α-Acylamino Acids with α-Chymotrypsin. IV. The Apparent Ionization Constants of a Series of Phenylalanine Derivatives. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/GJ3M-A585. https://resolver.caltech.edu/CaltechETD:etd-03272006-084330

Abstract

The consequences of systematic error in enzyme kinetics were investigated. Systematic error in substrate blank, enzyme blank, velocity determination, substrate concentration and the Beer-Lambert relationship was considered. The advisability of using weighting procedures in the presence of systematic error was questioned.

L-Tyrosyl-L-tyrosine methyl ester, amide, hydrazide and hydroxamide were prepared in order to detect transpeptidation in alpha-chymotrypsin-catalyzed hydrolyses. The reaction products from the hydrolyses of the corresponding L-tyrosine derivatives were found to contain only negligible amounts of transpeptidation products except for L-tyrosinhydroxamide which gave some L-tyrosyl-L-tyrosine. alpha- and beta-chymotrypsin were qualitatively the same with respect to these reactions.

The N-acetyl methyl esters of alpha-methylphenylalanine, alpha-methyltyrosine and alpha-methyl-beta-(2-naphthyl)-alanine were synthsized and resolved. These esters are good competitive inhibitors of alpha-chymotrypsin. N-acetyl-(-) alpha-methyl-beta-(2-naphthyl)-alanine is a slowly hydrolyzed substrate of this enzyme. The inactivity of these esters toward alpha-chymotrypsin-catalyzed hydrolysis is a consequence of their inability to react further after complexing with the enzyme.

The pK'_a values of the alpha-ammonium groups of D,L-phenylalanine amide, thioamide, amidoxime, hydrazide, methyl ester and hydroxamide were determined. Comparison of these pK'_avalues with some for corresponding glycine derivatives shows the former to be 0.59 ± .04 pK units lower. The infrared spectra of these phenylalanine derivatives were determined in KBr.

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