Amino acid sequences of two trypsin inhibitors from winged bean seeds (Psophocarpus tetragonolobus (L)DC.). 
The trypsin inhibitor (WTI-1) purified from winged bean seeds is a Kunitz type protease inhibitor having a molecular weight of 19,200.  WTI-1 inhibits bovine trypsin stoichiometrically, but not bovine alpha-chymotrypsin.  The approximate Ki value for the trypsin-inhibitor complex is 2.5 X 10(-9) M. The complete amino acid sequence of WTI-1 was determined by conventional methods.  Comparison of the sequence with that of soybean trypsin inhibitor (STI) indicated that the sequence of WTI-1 had 50% homology with that of STI.  WTI-1 was separated into 2 homologous inhibitors, WTI-1A and WTI-1B, by isoelectric focusing.  The isoelectric points of WTI-1A and WTI-1B were 8.5 and 9.4, respectively, and their sequences were presumed from their amino acid compositions.