title: Isolation of antitumor proteins abrin-A and abrin-B from Abrus precatorius.
abstract: Two toxic proteins were purified from the seeds of Abrus precatorius by DEAE-A 50 and Sepharose 4B chromatography. One of them does not bind on the Sepharose 4B column (Abrin-b) and the other (Abrin-a) is eluted with 0.2 M galactose. The amino acid compositions and tryptic maps of these two proteins were similar, but not identical. The molecular weights estimated by SDS-gel electrophoresis were 67,000 for abrin-b as compared with 65,000 for abrin-a. In the presence of mercaptoethanol, both abrin-a and abrin-b gave rise to two bands. The lethal doses of abrin-a and abrin-b for mice recorded within 48 h were 10 and 25 microgram per kg of body weight respectively. Abrin-a at 0.8 microgram per ml concentration level agglutinated human 0-type erythrocytes, whereas abrin-b showed no such activity. Abrin-a at 5 microgram per ml concentration level agglutinated both the Sarcoma 180 cells and Ehrlich ascites tumor cells, but it required 150 microgram per ml for abrin-b. Both these two proteins at a sublethal dose could inhibit the growth of Ehrlich ascites tumor cells which were injected simultaneously with these proteins. 131I-abrin-a and 131I-abrin-b were able to bind Sarcoma 180 cells, and the binding of abrin-a could be inhibited by lactose, raffinose, galactose and rhamnose, but none of 15 sugars tested inhibited the binding of abrin-b.
mesh_terms: D000036:Abrin / Q000032:analysis / Q000302:isolation & purification* / Q000633:toxicity; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D000970:Antineoplastic Agents; D002286:Carcinoma, Ehrlich Tumor / Q000188:drug therapy; D002846:Chromatography, Affinity; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D007928:Lethal Dose 50; D008297:Male; D051379:Mice; D008970:Molecular Weight; D037121:Plant Lectins; D010940:Plant Proteins / Q000302:isolation & purification*; D011485:Protein Binding / Q000187:drug effects; D012513:Sarcoma, Experimental / Q000188:drug therapy; D012639:Seeds / Q000032:analysis*; D014357:Trypsin / Q000494:pharmacology
chemical_list: D000596:Amino Acids; D000970:Antineoplastic Agents; D037121:Plant Lectins; D010940:Plant Proteins; D000036:Abrin; D014357:Trypsin