SERPINS FROM WHEAT-GRAIN

Wheat serpin genes have been identified by Southern blot hybridization with three distinct barley protein Z probes. Immunoblot analysis with a monoclonal antibody towards barley protein Z confirmed expression o f related M(r) similar to 40 kDa proteins in wheat grain. The wheat se rpins were extracted under reducing conditions and separated from beta -amylase and other seed proteins by thiophilic adsorption and anion-ex change chromatography. One molecular form possessing chymotrypsin inhi bitory activity was isolated in a reactive site cleaved form on a chym otrypsin affinity column. N-terminal amino acid sequences of a CNBr fr agment and of the C-terminal peptide from the cleaved inhibitor (M(r) 4574 +/- 4 Da) verified homology with barley protein Z and mammalian s erpins. The native inhibitory serpin was demonstrated to form an SDS-s table complex with alpha-chymotrypsin.