356 Properdin Factor D : Active Site
نویسنده
چکیده
Properdin factor D,1 a 23,500 tool wt euglobulin (6), interacts with properdin factor B and cobra venom factor (CoVF) to generate the CoVF-dependent C3 convertase which cleaves C3 (7) and activates the terminal complement components, C5-C9 (8). Fluid phase C3b, the major cleavage fragment of C3, interacts with factors B and D in a manner analogous to CoVF to form a fluid phase C3b-dependent C3 convertase (4). More recently, C3b bound to a sheep erythrocyte has been shown to react with factors B and D to generate a cell-bound C3b-dependent C3 convertase, EAC43B(D), which, like the classical cellular intermediate, EAC142, activates C3-C9 to bring the lytic sequence to completion (9). In the present study, factor D is shown to be inhibited by diisopropylphosphofluoridate (DFP) and derived from a previously unrecognized DFP-resistant precursor protein of similar molecular weight.
منابع مشابه
Properdin Factor D: Characterization of Its Active Site and Isolation of the Precursor Form
The activity of properdin factor D was measured by the generation of the hemolytically active cellular intermediate, EAC43B(D), bearing the C3b-dependent alternate pathway C3 convertase. Treatment of factor D with DFP prevented formation of EAC43B(D); thus, a serine esterase is essential for the generation of the alternate pathway C3 convertase, a situation analogous to the role of C1 in the fo...
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