ISOLATION AND CHARACTERIZATION OF A NOVEL RIBOSOME-INACTIVATING PROTEIN, BETA-KIRILOWIN, FROM THE SEEDS OF TRICHOSANTHES KIRILOWII

A novel ribosome-inactivating protein designated beta-kirilowin was is olated from the seeds of Trichosanthes kirilowii. The proteins exhibit ed strong abortifacient activity in pregnant mice and produced a singl e band after SDS-polyacrylamide gel electrophoresis with an apparent m ol. wt. of 27,500 daltons. It was active in inhibiting the cell-free t ranslation system with an ID50 of about 1.8 ng/ml. No crossreactivity with trichosanthin could be detected by immunodiffusion. Sequence comp arison of the first 10 residues of beta-kirilowin with ribosome-inacti vating proteins isolated from T. kirilowii such as trichosanthin, tric hokirin and karasurin indicated 70%, 60% and 70% identity, respectivel y. (C) 1994 Academic Press, Inc.