GB671042A - Improvements in or relating to a process for the manufacture of amino acids - Google Patents

Abstract

In a process for the selective separation of lysine, arginine and histidine from a hydrolysed protein containing them and other amino acids, the pH value of the hydrolysate is adjusted to at least 7.5 but not above a value at which lysine and arginine are substantially completely absorbed and the hydrolysate is then passed in contact with a body of loose, particulation exchange material which operates in the salt cycle whereby the lysine and arginine of the hydrolysate are retained in the ionexchange material while the histidine remains in the effluent for subsequent separation. The effluent may then be adjusted to a pH value between 5 and 6 and passed in contact with a second body of loose particulate cation-exchange material whereby the histidine contained in the first effluent is retained in the second body of cation-exchange material, and the other amino-acids (from the protein hydrolysis) remain in the effluent from the second body of cation-exchange material. The absorbed amino acids may be eluted as their monohydrochlorides with a salt solution, e.g. calcium chloride, Glauber salt, or, preferably sodium chloride. The mixed lysine and arginine salts are separated from, e.g. sodium chloride by concentration in vacuo, the addition of alcohol, and filtration of the hot solution from precipitated salt. On cooling lysine monohydrochloride precipitates and is filtered off. The arginine in the filtrate may then be obtained by evaporation or by precipitation with flavianic or by sulphonic acids, e.g. naphthalene b -sulphonic acid or 3,4-dichloro-benzene sulphonic acid. The histidine eluate is similarly freed from salt. The effluent from the histidine adsorption may be subjected to further ion-exchange processes to separate dicarboxylic amino acids, e.g. citrulline and hydroxylysine. In examples the process is applied to mixed amino acids obtained by hydrolysing (1) hog's blood, or protein separated therefrom by passing live steam; (2) wheat germ protein; (3) casein: (1) yields pure 1(+)lysine and 1(-)histidine and crude arginine. In (2) the eluate containing crude arginine is purified by crystallization of the naphthalene b -sulphonic acid or 3,4-dichlorobenzene sulphonic acid salt. In (3) the p casein, after hydrolysis with HC1, the hydrolysate is concentrated by boiling and then de-acidified in a column containing anion-exchange material to remove aspartic and glutamic acids and any residual HC1. These acids may be recovered by elution.