Lectins from Abrus Precatorius and Ricinus Communis

[摘要] The quantitative precipitation reactions of rabbit anti-abrin and anti-ricin sera have been studied with the purified toxins, abrin, and ricin, their isolated A- and B-chains and with the corresponding nontoxic Abrus and Ricinus agglutinins. In the case of ricin, the results are consistent with a model in which the agglutinin contains two lactose-binding B-chains, immunologically indistinguishable from the single B-chain of ricin and two A-chains which lack certain antigenic determinants present on the ricin A-chain. The relation between abrin and its agglutinin appears basically similar, although somewhat more complex. Both Abrus and Ricinus lectins react with lactose and with glycoproteins containing terminal nonreducing galactose residues that are present on certain proteins in the normal serum of many animal species and on the membranes of animal cells. Therefore precipitation reactions must be carried out in the presence of lactose or galactose. Dose-response curves of the effect of abrin and ricin on protein synthesis in HeLa cells are shown in the absence and presence of lactose. A method for estimation of potency of ricin antitoxin using the HeLa cell system is described.

[学科分类] 生物科学（综合）