Displacement chromatography on synthetic ion-exchange resins. 2. The separation of organic acids and acidic amino-acids by the use of anion-exchange resins

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Abstract
2. The suitability of Amberlite IR4, Wofatit M and De-Acidite B for displacement chromatography on a preparative scale was investigated. These commercial anion-exchange resins have weakly acidic properties in addition to their function as insoluble bases. The boundary widths given by glutamic acid with columns of these resins are approx. inversely proportional to the absorb-tive capacity of the resins. While some separation of glutamic and aspartic acids was achieved on De-Acidite B, it is probably not adaptable to practical use. The resins can be used to separate glutamic and aspartic acids from neutral amino acids, particularly serine. With De-Acidite B glutamic and aspartic acids can be separated by development with acetic acid. A charcoal-treated hydrolysate of commercial egg albumin was fractioned on a Zeo-Karb 215 column by displacement with NH4OH. Analysis of the chromatogram by paper chromatography showed that the mixture had been resolved into 7 bands: aspartic acid; glutamic acid, serine and threonine; glycine and alanine; valine and proline; leucine, isoleucine, methionine and cystine; histidine and an unidentified amino acid; and lysine. Tyrosine and phenylalanine, which interfere with the separation, had been removed by the charcoal treatment. A total recovery of 45.6% based on the wt. of dry protein was obtained in crystalline solids of amino acids and amino acids mixtures by evaporating appropriate fractions of the effluent solns. The isolation of the individual amino acids was discussed and suggestions given.