Marshall, Thomas H. (Professor of chemistry)||Kevill, Dennis N.||Erman, James E.
M.S. (Master of Science)
Department of Chemistry
The p-nitrophenyl esters of a homologous series of straight chain fatty acids were used as substrates for elastase and chymotrypsin. As the straight chain length increases, the deacylation rate of the acyl-enzyme increases regularly to a maximum and then declines. Examination of the activation parameters reveals that the degree of specificity results from enthalpy control rather than entropy. This appears to contradict, in varying degrees, the results of three previously published studies of chymotrypsin deacylation. Arguments are presented that some of the discrepancy can be explained in terms of different experimental methods being used and a detailed examination of the deacylation process in light of current theories of protein conformation. Elastase catalyzed hydrolysis of p-nitrophenyl N-benzyloxycarbonyl glycinate (CBZ-Gly-pNPE) and p-nitrophenyl t-butyloxycarbonyl-L-alaninate (NBA) are studied. The heat of ionization of the essential group in the active site of elastase, presumably histidine, is measured and discussed.
Chen, Violet W., "Activation parameters for deacylation of acyl-elastase and acyl-chymotrypsin" (1972). Graduate Research Theses & Dissertations. 981.
Northern Illinois University
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