Abstract: A trypsin inhibitor named TCTI was isolated from the rhizomes of Tinospora crispa (Menispermaceae) by trichloroacetic acid precipitation, salting out, chromatography on trypsin-Sepharose 4B and SHyperTM10 FPLC column, preparative PAGE and electroelution. The relative molecular weight of TCTI was 10.0kD by TSDS-PAGE. The inhibition of trypsin by the TCTI was competitive, with a Ki value of 2.08×10-7mol/L(BANPA as substrate) and the mole ratio was about 1:3.5. TCTI was heat- tolerating. When heated up to 100C for 60 min, it still had 93% residual activities. On the other hand, TCTI can be easily crystalized under lower temperature.

Key words: Tinospora crispa