title: [Description of an unusual enzymic activity cleaving the third component of complement].
abstract: A large enzymatic complex cleaving C3 (C3'ase) in the absence of magnesium (EDTA) has been partially characterized in two patients. On gel filtration EDTA-C3'ase was found in an 800 000 fraction containing antigenic C4, IgA and IgG in addition to alpha-2-macroglobulin and IgM normally present. EDTA-C3'ase was specifically neutralized by antibodies to IgG, IgA and C4. The characteristics of this unusual enzymatic complex are compatible with that of a C4b2a complex stabilized by its specific binding to an auto-antibody of the IgG and/or IgA class.
mesh_terms: D002850:Chromatography, Gel; D003166:Complement Activating Enzymes / Q000097:blood*; D050577:Complement C3-C5 Convertases / Q000097:blood* / Q000276:immunology; D004355:Drug Stability; D004492:Edetic Acid; D006358:Hot Temperature; D006801:Humans; D008970:Molecular Weight; D009097:Multienzyme Complexes / Q000097:blood*; D013379:Substrate Specificity
chemical_list: D009097:Multienzyme Complexes; D004492:Edetic Acid; D003166:Complement Activating Enzymes; D050577:Complement C3-C5 Convertases
vernacular_title: Description d'une activité enzymatique inhabituelle clivant le 3e composant du complément.