Studies on the Purification and Properties of L-Leucine. Studies on the Mode of Action of Trypsin and Chymotrypsin

• Main Author: Thomas, Dudley Watson
• Format: Others
• Published: 1951
• Online Access: https://thesis.library.caltech.edu/10464/2/Thomas_DW_1951.pdf; Thomas, Dudley Watson (1951) Studies on the Purification and Properties of L-Leucine. Studies on the Mode of Action of Trypsin and Chymotrypsin. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/DKCB-ER97. https://resolver.caltech.edu/CaltechTHESIS:09272017-150651665 <https://resolver.caltech.edu/CaltechTHESIS:09272017-150651665>

<p>A procedure for the preparation of L-leucine is described and certain physical properties, useful for establishing the identity or purity, have been redetermined. The behavior of L-leucine in sulfuric acid and glacial acetic acid solutions has been investigated.</p> <p>Preliminary investigations of the tryptic hydrolosis of acetyl- and benzoyl-L-argininamide have been conducted. It was found that aqueous trypsin solutions are quite unstable, and thus not ideally suited for kinetic studies. L-Arginine-methyl ester was found to be rapidly split at pH 4.0, this pH being far removed from the expected optimum (i.e. pH 7-8).</p> <p>The kinetics of the α-chymotrypsin catalyzed hydrolysis of acetyl- and nicotinyl-L-tyrosinamide has been investigated at 25°C. and pH 7.8-8.0. Suitable rate expressions have been developed and the rate constants determined. The effect of various competitive inhibitors of α-chymotrypsin has been measured, and conclusions have been drawn relative to structure and affinity for the enzyme. It has been shown that the α-chymotryptic hydrolyses, so far investigated quantitatively, can be described in terms of the classical Michaelis-Menten enzyme-substrate complex theory.</p>