A Simplified Method for separating Amino-acid Mixtures from Protein Hydrolysates on One Ion-Exchange Column during Preparation

Abstract

MOST of the methods used for the separation of mixtures of amino-acids are based on the work of Moore et al.^1–3. Separation is achieved either on two columns, acidic amino-acids being separated on a ‘Dowex’ 1 anion-exchange column and the basic and neutral amino-acids on a ‘Dowex’ 50 cation-exchange column or by chromatography on one column on ‘Dowex’ 50 in the H-cycle, elution being carried out with citrate phosphate buffer solutions. Hamilton and Anderson⁴ recently described a semi-automatic method for these separations containing several improvements of the original process. These methods ensure good separation of amino-acids; the eluates, however, contain either the hydrochlorides of the amino-acid and hydrochloric acid or considerable amounts of salts, which are difficult to remove. An efficient method for the separation of amino-acids should permit separation in a small volume of the elution reagent in a short time; the buffers used should be removable by a simple method. Wilcox et al.⁵ used volatile buffers for the separation of aspartic and glutamic acid on an anion-exchange column. Vaněček et al.⁶ and Tomášek⁷, used volatile buffers successfully for the separation of peptides on ‘Dowex’ 50.