Isolation and characterization of trypsin inhibitor from opaque-2 corn seeds

Trypsin inhibitor was isolated from seeds of opaque-2 corn by affinity chromatography on a trypsin/Sepharose column. The two major forms of inhibitor eluted from the affinity column were separated by DEAE-cellulose chromatography in the presence of urea. One form of inhibitor is a single-chain protein that has a molecular weight of approximately 12,500; the second inhibitor has two polypeptide chains and appears to have been produced from the single-chain inhibitor by exposure to trypsin in the affinity chromatography step. The relationship of the inhibitor isolated from opaque-2 corn to an inhibitor previously isolated from an unspecified strain of maize by Hochstrasser et al. (Hochstrasser, K., Muss, M., and Werle, E. (1967) Z. Physiol. Chem. 348, 1337-1340) is discussed.