title: [Major complement inhibiting factors from the venom of the Central Asian cobra Naja naja oxiana].
abstract: The properties of two anticomplementic factors isolated by CM-Sepharose chromatography from the basic non-adsorbed on DEAE-Sepharose fraction of the Central Asian cobra Naja naja oxiana venom, were studied. Of these three factors (CFB-I, CFB-II and CFB-III) the latter had been characterized earlier. CFB-I was shown to be a protein with an N-terminal Asp and a molecular mass of about 39 kDa (data from gel chromatography); its content in the venom is 3.6 mg/g of dry venom. The protein inhibits mainly the classical pathway of the complement activation, being bound to component C4 (Ki = 9 nM). CFB-I seems to be analogous to the CI inhibitor from the venom of the Naja haje cobra. An analysis of the N-terminal sequence of CFB-II showed it to be identical to the earlier characterized cytotoxin I. CFB-I inhibits the formation of C3 convertase with Ki = 2.2-2.8 microM by way of binding to C4b and thus interfering with the component C2 sorption.
authors.forename: L V
authors.initials: LV
authors.lastname: Kozlov
authors.forename: B B
authors.initials: BB
authors.lastname: Shoĭbonov
authors.forename: V K
authors.initials: VK
authors.lastname: Antonov
mesh_terms: D000818:Animals; D015941:Complement Hemolytic Activity Assay; D003169:Complement Inactivator Proteins / Q000032:analysis*; D003171:Complement Pathway, Classical / Q000187:drug effects; D004546:Elapid Venoms / Q000032:analysis* / Q000494:pharmacology; D004912:Erythrocytes / Q000276:immunology; D066298:In Vitro Techniques; D008970:Molecular Weight
chemical_list: D003169:Complement Inactivator Proteins; D004546:Elapid Venoms
vernacular_title: Osnovnye faktory iada sredneaziatskoĭ kobry Naja naja oxiana, ingibiruiushchie komplement.