Amino acid esterase activities of swine kidney.

As long ago as 1905, Warburg (1) employed the amino acid esterase activity of tissues to prepare the optical isomers of amino acids. Since that time, other than for the studies of esterase activity of the proteases, there have been only scattered reports of the amino acid esterase activity of tissue extracts. In fact, Smith and coworkers (24) have emphasized that their preparations of “leucine aminopeptidase” of swine kidney did not hydrolyze the methyl ester of leucine. In the course of our studies of the peptidases of swine kidney (5), it became apparent that amino acid esterase activities were concentrated along with the peptidase activities. These amino acid esterase activities appear to have the same specificity as the peptidases with which they are found; they do not hydrolyze simple esters or triglycerides and seem to be specific for the esters of amino acids of the L configuration.