title: A major phospholipase A2 from Daboia russelii russelii venom shows potent anticoagulant action via thrombin inhibition and binding with plasma phospholipids.
abstract: This is the first report on antithrombin effects of a phospholipase A2 (RVAPLA2) purified from venom of Daboia russelii russelii. The N-terminal sequence as well as in-gel tryptic digested peptides of RVAPLA2 showed significant homology with PLA2s from Russell's viper venom. RVAPLA2 demonstrated highest specific activity in hydrolyzing phosphatidylcholine (1.8 × 10(6) U/mg) with Km and Vmax values of 0.61 mM and 132.3 μmol/min, respectively. RVAPLA2 exerted dose-dependent catalytic and strong anticoagulant activities; however, studies indicated dissociation of its catalytic and anticoagulant sites. The anticoagulant action of RVAPLA2 was partially contributed by catalytic hydrolysis of plasma phospholipids. RVAPLA2 showed strong anticoagulant effect via thrombin inhibition with a Ki value of 380 nM as well as by binding to pro-coagulant phospholipids of plasma. In ex-vivo conditions, RVAPLA2 (1.0 μM) was non-hemolytic and non-cytotoxic to mammalian cells. It did not inhibit the collagen-induced aggregation of platelets. RVAPLA2 at a dose of 5 mg/kg was not lethal to mice after 48 h of injection. It demonstrated in vivo anticoagulant activity possibly due to targeting thrombin and binding with plasma phospholipids.
authors: Department of Molecular Biology and Biotechnology, Tezpur University, Tezpur 784 028, Assam, India; School of Biological Sciences, University of Northern Colorado, Greeley, CO 80639-0017, USA. Electronic address: akm@tezu.ernet.in.
authors: Ashis K
authors: AK
authors: Mukherjee
mesh_terms: D000818:Animals; D000991:Antithrombins / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D001777:Blood Coagulation / Q000187:drug effects; D051379:Mice; D008815:Mice, Inbred Strains; D054467:Phospholipases A2 / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D010743:Phospholipids / Q000097:blood*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D030162:Reptilian Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D017840:Daboia; D020539:Sequence Analysis, Protein; D013379:Substrate Specificity; D013917:Thrombin / Q000737:chemistry; D014757:Viper Venoms / Q000201:enzymology*
chemical_list: D000991:Antithrombins; D010743:Phospholipids; D030162:Reptilian Proteins; D014757:Viper Venoms; D054467:Phospholipases A2; D013917:Thrombin
keywords: Anticancer; Anticoagulant; Neutralization; Phospholipase A(2); Russell's viper; Thrombin inhibition