トリプトファンとパラジメチルアミノベンツアルデヒドの呈色の安定性に及ぼすアミノ酸その他化合物の影響

Abstract

The Ehrlich reaction, the blue coloration formed by the reaction of tryptophan and p-dimethylaminobenzaldehyde in strong acid solution, is accelerated by heating the solution or by the addition of an oxidation agent but at the same time, the color becomes unstable and liable to be discolored. In this case, the addition of acid hydrolyzate of proteins effects stabilization of coloration and prolongation of the maintenance period of maximum coloration. In order to find substances which can stabilize this coloration, various amino acids were submitted to the test. It was found that methionine effected the greatest stabilization of the color, the color formed having been maintained over three months. This was followed by cystine, tyrosine, histidine, aspartic acid, and glutamic acid, which possessed a certain amount of stabilization effect, while the action of other amino acids was weaker. As for compounds other than amino acid, levulic acid possessed a strong action similar to that of methionine, while pyruvic acid and fructose also possessed a fairly strong action. These results indicated that compounds possessing a sulfur atom or a carbonyl group possessed strong action. Based on these results, 0.1-1.0% solution of methionine was adopted as the solvent for the coloration solution of tryptophan, in place of acid hydrolyzate of proteins.