Amaranth globulin structure modifications induced by enzymatic proteolysis

Globulin-P was partially hydrolyzed with papain under specific conditions t o study the resulting structural modifications. Under mild hydrolytic condi tions, globulin-P polymers were cleaved to render their unitary constituent s (280 kDa molecules). Under stronger hydrolytic conditions these unitary m olecules were 13% smaller than those from nonhydrolyzed globulin. Moreover, these molecules remained assembled even though they contained degraded pol ypeptides. The monomeric (M) subunit and the A chains were preferentially c leaved under mild and intermediate hydrolytic conditions, whereas B chains remained with the same size. These results suggest that the M and A polypep tides might be located at an exposed site of the molecules resembling the s tructure of the legumins. The M subunit may be participating in the stabili zation of globulin-P polymers, on the basis that these two species disappea red under the same hydrolytic conditions. Similar events such as those desc ribed in this paper might be taking place on globulin-P during germination of amaranth grain.