Isolation of l-threonine from proteins

Abstract

Reaction of an esterified protein hydrolysate with benziminoethyl ether gave a mixture of products containing serine and threonine oxazoline derivatives. Alkaline hydrolysis to DL-benzoylserine and L-benzoylthreonine, separation of these by chromatography, and hydrolysis gave the amino acids. A 20% yield of L-threonine was obtained. L-serine was isolated from sericin by a modification of the oxazoline method.