Reduction of ricin toxicity without impairing the saccharide-binding properties by chemical modification of the carboxyl groups.
The usefulness of ricin as a research tool is handicapped by its extremely biohazardous nature. In this work, ricin toxicity has been reduced by chemical modification of carboxyl groups using 1-ethyl-3(3-dimethylaminopropyl) carbodiimide and [14C]glycine methyl ester. The reaction was carried out in 8 M urea and in the presence of 0.1 M lactose to protect the groups involved in saccharide binding. Together with carboxyl groups, tyrosine residues were also modified. The maximum modification achieved was 13 carboxyl groups and 7 tyrosines per molecule (about 30% of total carboxyls and tyrosines). The modification did not alter substantially the strength and specificity of the carbohydrate-binding ability of the lectin, as observed by hemagglutination tests and by inhibition assays with different carbohydrate structures. However, the LD50 decreased 90-fold when the highest modification was achieved. Therefore, the modified lectin can be used more safely in the study of galactose-containing carbohydrates.
Solís
D
D
Instituto de Química Física Rocasolano, Consejo Superior de Investigaciones Científicas, Madrid, Spain.
Vallejo
M
M
Díaz-Mauriño
T
T
D000818:Animals; D002250:Carbon Radioisotopes; D005022:Ethyldimethylaminopropyl Carbodiimide / Q000737:chemistry; D005998:Glycine / Q000031:analogs & derivatives / Q000737:chemistry; D006801:Humans; D007700:Kinetics; D007785:Lactose / Q000378:metabolism; D007928:Lethal Dose 50; D051379:Mice; D008807:Mice, Inbred BALB C; D011134:Polysaccharides / Q000378:metabolism*; D012276:Ricin / Q000737:chemistry / Q000378:metabolism* / Q000633:toxicity*; D013329:Structure-Activity Relationship
D002250:Carbon Radioisotopes; D011134:Polysaccharides; C035591:glycine methyl ester; D012276:Ricin; D007785:Lactose; D005022:Ethyldimethylaminopropyl Carbodiimide; D005998:Glycine