Direct production of l-ornithine from casein by commercial digestive enzymes and in situ activated arginase

Abstract

There is a great demand for L-ornithine, which is used as a dietary supplement, and in the pharmaceutical industry. In the present study, when milk casein was hydrolyzed at 37 degrees C by using commercial digestive enzymes, namely, Pancreatin F and Protease A, a significant accumulation of L-ornithine in the hydrolysate and the simultaneous disappearance of L-arginine was noted. In a radiometric assay, transient but distinct arginase activity, which was sufficiently high for L-ornithine production, was detected in the hydrolysate for a certain period during casein hydrolysis. On the basis of the results of the enzymatic analyses, arginase was thought to be proteolytically generated from an inactive precursor, which may generally be contained in Pancreatin F, and ultimately degraded by further proteolysis. This conversion process using the above-mentioned digestive enzymes is useful for the production of L-ornithine directly from protein sources that are abundant in nature.