RESUMEN
Objective:To extract the mung bean trypsin inhibitor(MBTI) from mung bean and to study the inhibitory activity of MBTI against proprotein convertases(PCs).Methods: MBTI was purified to homogeneity by ammonium sulfate precipitation, sequential chromatography of gel filtration,ion exchange,affinity chromatography and HPLC.The high expression strains of 2 PCs,Kexin and Furin,were selected.Kexin and Furin were purified by ammonium sulfate precipitation and gel filtration.The inhibitory activity of MBTI against Kexin and Furin was assayed and the inhibitory constants(Ki) of MBTI against the 2 PCs were calculated by Dixon's plot.Results:The purified MBTI showed a single peak on HPLC and a single band on SDS-PAGE.The inhibitory activity of MBTI against Kexin(Ki= 3.9?10~(-9)mol/L) was stronger than that against Furin.Conclusion: MBTI can inhibit both Kexin and Furin,especially Kexin,and also can be an ideal inhibitor against PCs after further modification.