Complete amino acid sequences and disulfide cross-link arrangements have been determined for the two subunit polypeptides (M r 9401 and 4597) ofconglutin δ, a helix-rich seed protein from Lupinus angustifolius cv. Uniwhite. There are two intrachain disulfide bonds and a free sulfhydryl group within the large chain and two interchain disulfide bonds to the small chain. The sequences show regions enriched in glutamineglutamic acid and serine residues which were correlated by a predictive method to the high measured level of α-helix (~ 38%). Homology was found between a cystine-rich region ofconglutin δ and the C-III α-amylase inhibitor from wheat suggesting that these proteins originated from a common ancestral gene.
