A method for the separation of peptides and α-amino acids

Abstract

1. Peptides and α-amino acids, occurring in mixtures from various sources, can be separated into one fraction containing the amino acids and several peptide fractions. This is achieved by chelation of the mixture with Cu²⁺ ions and subsequent chromatography of these chelates over the acetate form of diethylaminoethylcellulose or triethylaminoethylcellulose. 2. The amino acid fraction is obtained by elution with 0·01m-collidine–acetate buffer, pH8·0. 3. Peptide fractions are eluted with 0·01m-collidine–acetate buffer, pH4·5, 0·17n-acetic acid and 0·1n-hydrochloric acid respectively. 4. With the exception of aspartic acid and glutamic acid, which are partly found in the acidic peptide fraction, the amino acids are completely separated from the peptides. 5. Contamination of the acidic peptide fraction with glutamic acid and aspartic acid can be largely avoided by previous addition of an excess of arginine. 6. Copper is removed from the eluates by extraction with 8-hydroxyquinoline in chloroform.