Separation of D- and L-amino acids by ion exchange column chromatography in the form of 2-sulfonic acid alanyl dipeptides

Abstract

A method of ion exchange column chromatography was developed for the determination of D- and L-amino acids in the form of diastereomer dipeptide. First the protein containing samples were hydrolized with 6 mole hydrochloric acid then the single amino acids were separated in an LKB automated amino acid analyzer with the LKB fraction collector. Following lyophilization the single amino acids were transformed with (t-BOC)₂-L-CySS-(ONSu)₂ active ester into 2 sulfonic acid-alanyl dipeptide after inserted oxidation by performic acid. The 2-sulfonic acid-alanyl dipeptides appear on the chromatogram directly after cysteic acid. They separate easily from one another and from the cysteic acid formed from the excess of active ester. Accuracy of the determination is satisfactory. The coefficient of variation amounts to 4–10%.

The use of the method is suggested to laboratories having an amino acid analyzer and wish to determine D- and L-amino acids in synthetic amino acids complements, peptides or natural materials.