Purification and characterization of proteinase inhibitors from adzuki beans (Phaseolus angularis).
Two proteinase inhibitors, designated as inhibitors I and II, were purified from adzuki beans (Phaseolus angularis) by chromatographies on DEAE- and CM-cellulose, and gel filtration on a Sephadex G-100 column. Each inhibitor shows unique inhibitory activities. Inhibitor I was a powerful inhibitor of trypsin [EC 3.4.21.4], but essentially not of chymotrypsin ]EC 3.4.21.1]. On the other hand, inhibitor II inhibited chymotrypsin more strongly than trypsin. The molecular weights estimated from the enzyme inhibition were 3,750 and 9,700 for inhibitors I and II, respectively, assuming that the inhibitions were stoichiometric and in 1 : 1 molar ratio. The amino acid compositions of both inhibitors closely resemble those of low molecular weight inhibitors of other leguminous seeds: they contain large amounts of half-cystine, aspartic acid and serine, and little or no hydrophobic and aromatic amino acids. Inhibitor I lacks both tyrosine and tryptophan residues. The molecular weights were calculated to be 7,894 and 8,620 for inhibitors I and II, respectively. The reliability of these molecular weights was confirmed by the sedimentation equilibrium and 6 M guanidine gel filtration methods. On comparison with the values obtained from enzyme inhibition, it was concluded that inhibitor I and two trypsin inhibitory sites on the molecule, whereas inhibitor II had one chymotrypsin and one trypsin inhibitory sites on the molecule.
D000596:Amino Acids / Q000032:analysis; D001665:Binding Sites; D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D002918:Chymotrypsin / Q000037:antagonists & inhibitors*; D004791:Enzyme Inhibitors / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D010944:Plants; D011485:Protein Binding; D014361:Trypsin Inhibitors / Q000032:analysis* / Q000302:isolation & purification / Q000494:pharmacology
D000596:Amino Acids; D004791:Enzyme Inhibitors; D014361:Trypsin Inhibitors; D002918:Chymotrypsin