Cytoagglutination by and toxicity of ricin D cross-linked with glutaraldehyde.

Abstract

Ricin D was cross-linked with glutaraldehyde. Cross-linked (CL-)ricin D was divided into three fractions, which contain the oligomer (trimer and tetramer), dimer, or monomer as the main components, by gel filtration on a Sephacryl S-200 column followed by DE-32 cellulose column chromatography. From the analyses of the unmodified lysyl residue in each fraction and the reduction product of the dimer-fraction on SDS-PAGE, it was suggested that ricin D was crosslinked by a single glutaraldehyde-link between any two chains, but more easily between two A-chains. Cytoagglutinating activity of the monomer, dimer, and oligomer fractions of CL-ricin D toward human erythrocytes were 2.2, 9, and 18 fold that of native ricin D, but the Cytoagglutinating activity toward SAT cells was identical to that of native ricin D. The inhibitory activities of these fractions on protein synthesis in HeLa cells were 38.6%, 4.9%, and 2.4% and those in SAT cells were 85%, 90%, and 42%, respectively. Toxicity toward mice was approximately 80%, 20%, and 7%, respectively.