SummaryPlatelet membrane glycoproteins (GP) are involved in platelet adhesion and aggregation. The glycoprotein IIb-IIIa complex (GP IIbIIIa) is a Ca2+-dependent heterodimer that binds fibrinogen and other adhesive proteins, thereby mediating platelet aggregation and adhesion. We have purified two major glycoproteins from pig platelets by Concanavalin A-Sepharose, Heparin-Sepharose and Sephacryl S-300 HR chromatography (Fitzgerald et al. Anal Biochem, 1985): i) the GP IIb-IIIa complex, GP IIb Mr = 140,000 and GP IIIa a single chain of Mr = 95,000-100,000; and ii) a predominant glycoprotein of high molecular weight, the propolypeptide of von Willebrand factor (Mr = 80,000-100,000). Western-blot analysis of the purified GP IIb-IIIa showed that only certain monoclonal antibodies against the human receptor specifically recognize the porcine complex. Differences between the porcine and human GP IIb-IIIa glycoproteins could partially explain the decreased inhibitory effects of GP IIb/IIIa-antagonists (against the human receptor) in porcine platelets.

HighlightsExperimental data placed PP-IX as an effective antimutagen at low doses.PP-IX could acts through the formation of chemical complexes with the chromium.Low concentration of PP-IX reduced genetic damage of the radiomimetic CrO3.The ability of PP-IX to release electrons may have inactivated the free radicals.Ferrochelatase could participate in the chelating chromium reducing its mutagenicity.