抄録
A trypsin inhibitor was extracted from rice bran with 1% sodium chloride and partially purified by 40_??_80% ammonium sulfate fractionation. The crude inhibitor obtained showed the inhibitory activity on trypsin [EC 3. 4. 21. 4] but not on a-chymotrypsin [EC 3. 4. 21. 1] or pepsin [EC 3. 4. 23. 1]. This inhibitor was stable at acidic and neutral pHs but was gradually inactivated by the long-time incubation with pepsin. The molecular weight of the inhibitor was estimated to be 13, 500 by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Furthermore, gel filtration on Sephadex G-75 suggested the possible self-association of the inhibitor. Isoelectric focusing demonstrated that the inhibitor is a basic protein having a pI value of 8.2. The inhibitor was adsorbed on to CM-Sephadex C-25 at pH 5.7, indicating that it can be further purified by this chromatography.
