HIGH-MOLECULAR-WEIGHT PRODUCTS OF HYDROLYSIS OF SOYBEAN GLYCININ BY TRYPSIN

Glycinin and pseudoglycinin were renatured from preparations of the in dividual subunits (A2B1a and A3B4), hydrolyzed with trypsin, and the c ompositions of the high molecular weight intermediates and final produ cts were analyzed The results suggest that the alpha-chains contain th ree structural domains, formed by their N-terminal and central regions (domains D1 and D2) and the C-terminal region proximal to the C-termi nal hypervariable region (domain D3). The central domain (D2) is limit ed by regions with increased sensitivity to proteolysis, their cleavag e initially resulting in the formation of large intermediate fragments of two types, those composed of domains D1 and D2 and those composed of domains D2 and D3 and the greater part of the hypervariable region. The limited C-terminal regions of both alpha- and beta-chains are als o characterized by increased sensitivity to proteolysis. The final pro duct of proteolysis, glycinin-T, is composed of fragments correspondin g to domain D1 that are covalently bound to beta-chains, to domain D2, and to domain D3 (at least in the A2 alpha-chain); some alpha-chains form fragments corresponding to the greater part of the hypervariable region, probably bound to domain D3 or to its C-terminal part.