Production and Applications of Corn Peptide Using Alkaline Protease from an Alkalophilic Bacillus Sp.
Magoichi YAMAGUCHI*a, Nobuyuki NAKAMURAa, Michiko ITOb, and Yuji FURUKAWAb
a Research Institute, Nihon Shokuhin Kako Co., Ltd., 30 Tajima, Fuji 417, Japan
b Department of Applied Biological Chemistry, Faculty of Agriculture, Tohoku University, 1- 1 Tsutsumidori Amamiya-cho, Sendai 981, Japan
Corn gluten meal is a by-product of the corn wet-milling process and consists mainly of zein which is rich in glutamic acid (glutamine), alanine, leucine and proline. Partial proteolysis is effective for improving the functional properties of the protein. For this purpose, protease has been used. Many investigations have been conducted about characterization (1) and kinetic analysis (2) of microbial alkaline protease. We prepared alkaline protease from alkalophilic Bacillus A-7 isolated from soil which can grow in high alkaline media with reference to Horikoshi's report (3) and then applied it to corn gluten meal. Consequently, corn peptide (CP) in which free amino acids were not found and the molecular weight distribution was less than about 2,000, characteristic of dipeptide to decapeptide, i.e. oligopeptides, could be produced. The amino acid pattern of CP was similar to that of corn gluten meal, which was rich in alanine, proline and branched-chain amino acid, but poor in basic amino acids.
On the other hand, we have reported that the administration of alanine and proline to stroke-prone spontaneously hypertensive rats (SHR-SP) increased in preference for alcohol and accelerated alcohol metabolism (4,5). Concerning alcohol metabolism in animals, the ability to metabolize alcohol is affected by nutritional conditions. It has been reported that absorption of oligopeptides in the small intestine is more rapid than that of the corresponding amino acid mixtures, and nutrition is apparently maintained by the oligopeptide uptake. When SHR-SP (6) or human (7) ingested CP prior to alcohol intake, the blood ethanol level was lower than the control without CP administration. In addition, CP ingestion significantly elevated plasma alanine and leucine. Hence, CP may have the effect on the reduction of increase in blood ethanol level after alcohol intake by the marked elevation of plasma alanine and leucine, and effectively takes part in enhancing alcohol metabolism. The potential beneficial effects of improving the therapy against the impairment of health or the alcoholic liver disease due to chronic alcohol consumption can be considered by the ingestion of CP.
1. Alder-Nissen, J. (1977) Proc. Biochem., 12, 18-32.
2. Julie, E. H. and Charles, E.G. (1989) Agric. Food Chem., 37, 1188-1192.
