The Fractionation of the Amino Acids of Livetin

Most of the schemes exist,ing for the analysis of proteins necessitate the use of large amounts of material. The need is great for a scheme which can be used with smaller amounts. It was felt that a combination of certain of the more generally accepted methods for amino acid determination could be arranged and an economy of original material be thus effected. The following scheme was eventually decided upon as a result of trial experiments. 1. The protein is hydrolyzed and humin, ammonia, and t,he basic amino acids are removed and estimated by the methods of Vickery and his coworkers (1). 2. The various mother liquors so obtained are freed from interfering substances and combined. Tyrosine is removed by crystallization. The filt,rate is treated w&h alcohol and baryta for the precipitation of the dicarboxylic acids. Aspartic and glutamic acids are removed and est.imated according to the directions of Jones and Noeller (2). Hydroxyglutamic acid is removed at t,his stage by precipitation of its silver salt. 3. The amino acids in the filtrate and mother liquors from this procedure are converted into their copper salts and separat.ed into three groups according to the method of Brazier (3). As eight amino acids have been removed, the scheme of Brazier becomes simplified as follows: (a) The copper salts insoluble in water include the salts of leucine and phenylalanine. The calorimetric method of Kapeller-Adler (4) for the estimation of phenylalanine facilitates the examination of this fraction. (b) The copper salts insoluble in methyl alcohol include the salts of glycine and alanine,