title: Isolation and characterization of the trypsin inhibitors from winged bean seed (Psophocarpus tetragonolobus (L) Dc.).
abstract: The trypsin inhibitors from winged bean seed were isolated by affinity chromatography on trypsin-Sepharose 4B and the components fractionated by chromatography on SP-Sephadex C-25 and Sephadex G-100. The major components, inhibitors 2 and 3 were found to be homogeneous proteins with molecular weights of about 20,000. The inhibitors stoichiometrically inhibited bovine trypsin in the molar ratio of 1 : 1 whereas the inhibition of bovine alpha-chymotrypsin was weak and non-stoichiometric. Amino acid analysis indicated that both the inhibitors contain four cysteine residues and are rich in aspartic acid, glutamic acid, glycine, valine and leucine; however, inhibitor 3 lacks histidine and methionine while inhibitor 2 contains one histidine and three methionines. A minor trypsin inhibitor fraction was also isolated which contained at least three proteins with a molecular weight of about 10,000 and a high content of half-cystine.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D007887:Fabaceae / Q000032:analysis*; D008970:Molecular Weight; D010940:Plant Proteins / Q000032:analysis; D010944:Plants / Q000032:analysis*; D010946:Plants, Medicinal; D013056:Spectrophotometry, Ultraviolet; D014361:Trypsin Inhibitors / Q000302:isolation & purification*
chemical_list: D000596:Amino Acids; D010940:Plant Proteins; D014361:Trypsin Inhibitors