RESUMEN
A new small ribosome-inactivating protein named S-trichokirin from the seeds of Trichosanthes kirilowii was purified by ammonia sulfate precipitation, CM-52 ion exchange chromatography, Sephacryl S-100 gel filtration and FPLC Mono S ion exchange chromatography. S-trichokirin has molecular weight about 8 kD, as determined by 15% SDS-PAGE and 15% Tris-Tricine PAGE. It was proved to be a strong basic protein with pI about pH 9.5 by 13.5% acidic PAGE. The reaction mechanism of S-trichokirin is the same as that of trichosanthin, which is an RNA N-glycosidase. It had a strong inhibitory effect on protein biosynthesis in rabbit reticulocyte lysate with IC(50) of 1.15x10(-10) mol/L. S-trichokirin may be used as a new efficient moiety of immunotoxin.
