Isolation and biochemical properties of toxic tryptic peptides of ricinotoxin from Ricinus communis seeds.

Tryptic hydrolysis conditions of ricinotoxin were studied in order to produce not only digestion of this glycoprotein but also still toxic tryptic peptides. No hydrolysis was obtained without prior denaturation. The best conditions of denaturation were obtained with 0.2 M guanidine hydrochloride and, to a lower extent, by heat treatment at 90 degrees C during 6 minutes. The hydrolysates were fractionated on Sephadex G100 column. In each case highly toxic peptide fractions were obtained which showed, like native ricinotoxin, a strong inhibitory action on the in vitro protein synthesis ina cell-free eukaryotic system but were without any action on a prokaryotic cell-free system.