The Resolution of Several Racemic Amino Acids

L-and n-alanine have been prepared in quantity and with a high degree of optical purity by a simple and convenient method based upon the following (1): (a) rat and hog kidney possess an enzyme which acts rapidly and asymmetrically upon N-acylated nn-alanine, hydrolyzing the acyl radical completely from the L form, and leaving the N-acylated D form intact; (b) from such a digest, the free n-amino acid can be separated by addition of alcohol, leaving the soluble acyl-n-alanine in the mother liquor; and (c) hydrolysis of the separated acyl-n-alanine by hot mineral acid, followed by neutralization, yields the free n-amino acid.The asymmetric action of the kidney preparations with N-acylated derivatives of several other amino acids suggested that this method might be extended to the resolution of amino acids other than alanine (1).The present communication describes such an extension to the resolution of the isomers of racemic methionine, valine, threonine, isoleucine, serine, leucine, and aspartic and glutamic acids.The resolution of the basic and aromatic-substituted amino acids, as well as that of proline, presents special problems and will be described later.EXPERIMENTAL