SEQUENCE OF A NEW BOWMAN-BIRK INHIBITOR FROM TORRESEA-ACREANA SEEDS AND COMPARISON WITH TORRESEA-CEARENSIS TRYPSIN-INHIBITOR (TCTI2)

TaTI (Torresea acreana trypsin inhibitor), a new member of the Bowman- Birk trypsin inhibitor family, was purified from seeds of Torresea acr eana, one of the two known species of Torresea, a Brazilian native Leg uminosae of the Papilionoideae subfamily. Purification was performed b y acetone fractionation, anion-exchange chromatography, and gel filtra tion. The TaTI appears as M(r) 7000 in SDS-PAGE under reducing conditi ons. There are 63 amino acid residues present in the TaTI sequence, wh ich was confirmed by mass spectrometry (8388 daltons). The putative re active sites residues were Lys-15 and Arg-42 at the first and second s ite, respectively. The antibodies raised against TcTI2, Torresea ceare nsis trypsin inhibitor 2, showed a cross-reaction with TaTI, but not w ith other Bowman-Birk inhibitors purified from Leguminosae. The inhibi tion constants of TaTI and TcTI2 were comparable when measured against trypsin, chymotrypsin, and factor XIIa, but not on plasmin. The latte r was tenfold more effectively inhibited by TcTI2 then by TaTI. Neithe r TaTI nor TcTI2 affects thrombin, plasma kallikrein, or factor Xa.