The Carbohydrate-binding Specificity of a Highly Toxic Protein from Abrus pulchellus Seeds

Autor: Liezelotte R. Bomfim, Renato de Azevedo Moreira, Socorro V. F. Madeira, Márcio V. Ramos, Clarissa Teixeira
Rok vydání: 1999
Předmět:
Zdroj: Memórias do Instituto Oswaldo Cruz., Vol 94, Iss 2, Pp 185-188 (1999)
ISSN: 0074-0276
DOI: 10.1590/s0074-02761999000200010
Popis: A highly toxic protein, which exhibits similareffects to ribosome inactivating proteins (RIPs typeII), isolated from Abrus pulchellus seeds kills micein a few hours after injection in the peritoneal cav-ity (MV Ramos et al. 1998a Toxicon 36: 477-484).It is well documented in the literature that sometoxins mediate their incursion by recognizingglycoconjugates on the cell surface membrane be-fore translation. Plant and microbial toxins havebeen studied in detail mainly to understand theirintrinsic toxic pathway. However, the toxin recog-nition mechanism by membrane receptors and itstranslation through the membrane is poorly inves-tigated, excepting abrin, the most investigated planttoxin. It has been determined that the initial recog-nition step must be mediated by carbohydrate-pro-tein interaction. The ribosome inactivating proteinfrom the seeds of Viscum album is a typical pro-tein of this class and its carbohydrate-binding speci-ficity was carefully investigated (H Debray et al.1994 Glycoconjugate J 11: 550-557). Althoughthe RIPs type II are commonly specific for galac-tose residues, more complex carbohydrates are dis-tinctly recognized.Thus, to well define the carbohydrate moietythat interacts with a toxin, a number of carbohy-drates (monosaccharides, di- tri- and oligosaccha-rides) and complex glycans from glycoproteinsshould be tested. In this respect, we have investi-gated the carbohydrate-binding specificity of atoxin from A. pulchellus seeds by the combinationof haemagglutination inhibition assay and affinitychromatography using immobilized glycoproteins.The toxin was isolated following the procedurepreviously described (Ramos et al. 1998a loc. cit. )and the haemagglutinating activity induced by thetoxin was studied using rabbit and human ORh
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