Open AccessMolecular weight of the membrane C5b-9 complex of human complement: characterization of the terminal complex as a C5b-9 monomer.
Author(s) -
Sucharit Bhakdi,
Jørgen TranumJensen
Publication year - 1981
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.78.3.1818
Subject(s) - sedimentation coefficient , monomer , chemistry , membrane , size exclusion chromatography , ultracentrifuge , complement membrane attack complex , stokes radius , complement system , analytical ultracentrifugation , hydrodynamic radius , centrifugation , micelle , molecular mass , chromatography , biochemistry , biology , enzyme , organic chemistry , aqueous solution , antibody , immunology , polymer
The hydrodynamic properties of the detergent-solubilized, terminal membrane complex of serum complement components C5-C9 [C5b-9(m)] were studied to obtain an estimate of its molecular weight. In a solution of Triton X-100/deoxycholate, the protein complex binds 17% Triton X-100 and 11% deoxycholate by weight. The sedimentation coefficient of the protein-detergent complex is 26 S as determined by sucrose density gradient ultracentrifugation, and gel filtration indicated a molecular radius of 11 nm. It was ascertained by electron microscopy that these hydrodynamic parameters apply to mono-dispersed C5b-9(m) complexes, which were observed as nonaggregated, hollow protein cylinders and were identical to the complement "lesions" formed on target membranes. The calculated molecular weight of the protein-detergent complex is approximately 1,286,300 to which the protein moiety contributes approximately 1,000,000. The results indicate that the C5b-9(m) complex formed on biological membranes is a monomer entity of the C5-C9 complement components.