The preparation of lysine from protein hydrolysates.

We have previously reported that acetone solutions containing certain organic acids form systems composed of amino acid-acetone-sulfonic acid (or alkyl acid phosphate) (1, 2), and have shown that by means of such systems amino acid mixtures may be fractionated in a non-aqueous medium. We here describe a method for the preparation of lysine monohydrochloride from an acid hydrolysate of casein, based upon the insolubility of a lysine-benzenesulfonic acid complex in acetone. This method is apparently applicable to protein hydrolysates generally, provided they are free from mineral acid and are well dried and ground. Our experience has been limited to hydrolysates of whole beef blood, whole blood clot, and serum protein, prepared with hydrochloric acid (supplied by The Wilson Laboratories, Chicago), and a hydrochloric acid hydrolysate of casein, freed from residual hydrochloric acid by treatment with a synthetic resin. This product bears the trade name Hycase.’ The unique feature of our method is the formation of a precipitate consisting of lysine and some histidine and benzenesulfonic acid in a system composed of amino acids and benzenesulfonic acid in acetone. If the hydrolysate contains inorganic impurities, some of these will be present in the precipitate. Procedure