Trichobitacin is a new ribosome-inactivating protein (RIP) isolated from the press-residue of the fresh root tube of Trichosanthes kirilowii Maxim, Cucurbitaceae. Its molecular weight is 27, 228, and pI 9.6. From the mass peptides maps, determined by matrix-assisted laser desorption ionization-time of flight-mass spectrometry (MALDI-TOF-MS) and fast atom bombardment mass spectrometry (FAB-MS) of trichobitacin and trichosanthin digested by trypsin respectively, some corresponding peptides have been found. Because both of trichobitacin and trichosanthin are isolated from the root tube of Trichosanthes kirilowii Maxim, they are homologous, the amino acid sequences of the two proteins may be very similar, so these peptides may have similar sequences in two proteins. In addition to the results of protein N-terminal sequencer, the N-terminal 38 amino acids sequence of the trichiobitacin has been determined, and more than 100 amino acids sequences have also been determined by the methods of protein automatic sequencer and manual DABITC/PITC double coupling as well as mass spectrometry respectively.

Key words: RADIX TRICHOSANTHIS, CHEMICAL STRUCTURE, TIME-OFF FLIGHT MASS SPECTROMETRY, TRICHOSANTHES ANGUINA