The amino-acid composition of tyrocidine

Abstract

Technical modifications have extended quantitative analysis by partition chromatography to a further group of amino-acids. From an acid hydrolysate of tyrocidine, phenylalanine, leucine, proline, valine, tyrosine, ornithine and glutamic acid have been isolated by partition chromatography, and characterized as their acetyl derivatives. Additional evidence has been obtained for the occurrence of tryptophan and aspartic acid. This appears to be the first isolation of ornithine by acid hydrolysis of an intact protein or polypeptide. The phenylalanine isolated had mainly the d-configuration; the other amino-acids were mainly l-. 88-105% of the N of tyrocidine has now been accounted for, but the variability of the analytical figures has not permitted stoichiometric calculations. The implications of this variability which exceeds the analytical errors, are discussed.