A new technique for the estimation and isolation of the hexone bases in protein hydrolysates

Abstract

Aromatic amino acids are removed by passage of the hydrolysate at pH 2-3 over charcoal, and washing the charcoal with water until the water is ninhydrin-unreactive. The bases of the combined filtrate and eluate at pH 7-8 are converted to picrates. The picrates are passed over charcoal and the charcoal washed with water until the eluates are ninhydrin-unreactive. The picrates of the hexone bases are retained on the charcoal and treatment with 0.5 N HC1 or H2SO4 releases the bases. Hydroxylysine and lysine are separated from ammonia and detd. by the micro-Kjeldahl method. Elution with [image] acid releases histidine and arginine, which are estimated colorimetrically. The method was used for gelatin hydrolysates and the following were found: arginine, 15.20; histidine, 1.0; lysine, 4.6; and hydroxylysine, 0.87% of the gelatin N.