Comparative digestibility of legume storage proteins

Abstract

Native and heated legume storage proteins were digested with various proteinases. Gel electrophoresis patterns indicated that phaseolin (dry bean) was most resistant to digestion, vicilin (pea) was most susceptible, and glycinin and P-conglycinin (soybean) were intermediate in susceptibility to various proteinases. The native proteins were cleaved by trypsin and chymotrypsin in only limited areas of the molecule, but they were all readily degraded upon heating. N-Terminal sequence analysis of the major breakdown products from phaseolin digestion and hydrophilicity and surface probability determinations indicated that trypsin, chymotrypsin, and papain cleave native phaseolin near the center of the protein molecule at a hydrophilic region predicted to be on the surface. This region in phaseolin is highly homologous in sequence with hydrophilic regions in vicilin and P-conglycinin.