title: [Complement-inhibiting acidic factors from the venom of Central Asian cobra Naja naja oxiana].
abstract: Two anticomplementic factors isolated from the venom of the Central Asian cobra Naja naja oxiana by chromatography on DEAE-Sepharose CL-6B and subsequent gel filtration on Sephacryl S-200 were studied. Of these, five factors (CFA-Ia, CFA-Ib, CFA-Ic, CFA-IIa and CFA-IIb), CFA-Ib had been characterized earlier, while CFA-Ia was assigned to a previously identified H-CoF factor. It was shown that CFA-Ic has a molecular mass of 3900 Da; its content in the venom amounts to 2.6 mg/g of dry venom. This factor inhibits the classical pathway of C3 convertase formation abrogating the C2 component activation by subcomponent C1s [Ki = (2.5 +/- 0.8).10(-7) M]. CFA-IIa and CFA-IIb are present in the venom in very low amounts (2 mg/g) and have Mr of 5700 and 3200 Da, respectively. The complement-inhibiting action was studied for a more active CFA-IIa. Factor CFA-IIa was shown to inactivate the native component of C2 with a rate constant, k, of (2.7 +/- 0.2).10(3) s-1M-1 (37 degrees C, pH 7.4). CFA-IIa had no effect on C2 and C2a within their complexes with C4b.
authors.forename: B B
authors.initials: BB
authors.lastname: Shobonov
authors.forename: L V
authors.initials: LV
authors.lastname: Kozlov
authors.forename: V K
authors.initials: VK
authors.lastname: Antonov
mesh_terms: D002848:Chromatography, DEAE-Cellulose; D050577:Complement C3-C5 Convertases / Q000037:antagonists & inhibitors; D003169:Complement Inactivator Proteins / Q000302:isolation & purification*; D004546:Elapid Venoms / Q000302:isolation & purification* / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008970:Molecular Weight
chemical_list: D003169:Complement Inactivator Proteins; D004546:Elapid Venoms; C016310:cobra venom factor; D050577:Complement C3-C5 Convertases
vernacular_title: Kislye faktory iada sredneaziatskoĭ kobry Naja naja oxiana, ingibiruiushchie komplement.