Studies on Leucine and Dileucine Hydrochloride and a New Method for the Isolation of Leucine

The Isolation and Synthesis of the Naturally Occurring a-Amino Acids.

“…Most of the commercial "leucine" contains considerable quantities of isoleucine, valine, and even methionine. Barnett (22,23) isolated leucine as dileucine hydrochloride from a neutralized casein hydrolysate at pH 1.7-2.8 in the presence of a large excess of sodium chloride, while Stein el al. (301) used 2-bromotoluene-5-sulfonic acid to precipitate leucine from a leucinerich, isoleucine-poor protein hydrolysate (hemoglobin).…”