W. Fones, M. Lee
Apr 1, 1953
Citations
0
Influential Citations
22
Citations
Journal
The Journal of biological chemistry
Abstract
The asymmetric hydrolysis of N-acyl derivatives of m-amino acids by an enzyme (acylase I) prepared from hog kidneys has been used by Greenstein and his coworkers for the resolution of numerous amino acids (see Birnbaum et al. (1) for references). Usually either the acetyl or chloroacetyl derivatives of the amino acids have been utilized because of their ready availability and because in most cases they are quite susceptible to the action of the enzyme. That the utilization of other N-acyl groups is feasible has been shown by the resolution of m-glutamic acid by asymmetric hydrolysis of its carbobenzoxy derivative (2). Other N-acyl derivatives of alanine known to be attacked by this enzyme are propionyl, formyl, benzoyl (3), and glycyl (4). The study reported here was undertaken to shed further light on the relation of substrate structure to enzyme susceptibility and to determine whether some acyl derivatives of amino acids ot’her than acetyl or chloroacetyl might be more advantageously employed in the resolution of amino acids. The data obtained indicate that both electronic and steric factors operate in determining the relative susceptibility of the various N-acyl derivatives of alanine and phenylalanine to hydrolysis by acylase I. Although both the fluoroacetyl and trifluoroacetyl derivatives of each of these amino acids are hydrolyzed at a faster rate than the corresponding chloroacetyl derivative, neither substituent group is a promising one for use in amino acid resolution with acylase I. The former derivatives are too difficult to prepare and in the latter instance the N-trifluoroacetyl-n-amino acid component of the racemate is appreciably hydrolyzed. The rates of cleavage of the N-acyl derivatives of phenylalanine by crystalline pancreatic carboxypeptidase are also reported, since this enzyme has been employed for the resolution of several amino acids containing a phenyl group (5). In this instance the steric effect appeared to be less important than the electronic effect although probably still occurring. The trifluoroacetyl derivative of phenylalanine was hydrolyzed at a rate much greater than that of any of the other N-acyl derivatives, and, since the