title: A characterization of abrin A from the seeds of the Abrus precatorius plant.
abstract: Abrin A was purified from the seeds of the Abrus precatorius plant and its physical and biological properties were studied. The biological properties of abrin A were found to be similar to the better studied Abrus protein, abrin C, in that it is toxic to cell-free protein synthesis and binds D-galactose. Abrin A contains carbohydrate moieties including both neutral and amine sugars but no metals, similar to the other two Abrus proteins (abrin C and the Abrus agglutinin). Amino acid compositions of the subunits of abrin A indicated that it consists of two different subunits of comparable size. Furthermore, one of the subunits showed microheterogeneity suggesting that abrin A is a mixture of isolectins. A comparative study of abrin A and abrin C based on compositions and tryptic maps reveals them to be closely related. The evidence suggests that the two abrins may have the same mechanisms of toxic action. Far-ultraviolet circular dichroic studies of abrin A show it to contain 47% beta-pleated sheet and 10% alpha-helix, again similar to the other two Abrus proteins.
mesh_terms: D000036:Abrin / Q000302:isolation & purification* / Q000633:toxicity; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002241:Carbohydrates / Q000032:analysis; D002474:Cell-Free System / Q000187:drug effects; D007887:Fabaceae / Q000032:analysis*; D006386:Hemagglutination Tests; D006801:Humans; D046911:Macromolecular Substances; D037121:Plant Lectins; D010940:Plant Proteins / Q000302:isolation & purification*; D010946:Plants, Medicinal; D010947:Plants, Toxic / Q000032:analysis*; D011487:Protein Conformation; D011817:Rabbits; D012156:Reticulocytes / Q000187:drug effects; D012639:Seeds / Q000032:analysis
chemical_list: D000596:Amino Acids; D002241:Carbohydrates; D046911:Macromolecular Substances; D037121:Plant Lectins; D010940:Plant Proteins; D000036:Abrin