Fluid-phase SC5b-8 complex of human complement: generation and isolation from serum.
A rapid, simple method for isolating SC5b-9 generated in human serum, and SC5b-8 generated in C9-depleted serum is described. The procedure leads to approximately 30% recovery of either complex and consists of polyethyleneglycol precipitation followed by 1 DEAE ion exchange chromatography and a sucrose density gradient ultracentrifugation. The SC5b-8 complex is a water-soluble macromolecular of alpha-electrophoretic mobility. Apart from the absence of C9, it exhibits an identical SDS-gel electrophoresis polypeptide pattern as SC5b-9. A sedimentation coefficient of 19 to 20S and an effective molecular radius of approximately 10 nm were determined by sucrose density gradient centrifugation and gel filtration, respectively. From these values, a m.w. of 800 to 850,000 is tentatively assigned to the SC5b-8 complex. The S-protein was not dissociable from either SC5b-8 or SC5b-9 through treatment with desoxycholate and no alterations in the hydrodynamic properties of either complex were discernible after action of this detergent.
D000510:Alpha-Globulins / Q000302:isolation & purification*; D001798:Blood Proteins / Q000378:metabolism; D002499:Centrifugation, Density Gradient; D011232:Chemical Precipitation; D015938:Complement Membrane Attack Complex; D003165:Complement System Proteins / Q000172:deficiency / Q000302:isolation & purification*; D006801:Humans; D007123:Immunoelectrophoresis, Two-Dimensional; D011485:Protein Binding
D000510:Alpha-Globulins; D001798:Blood Proteins; D015938:Complement Membrane Attack Complex; C030931:SC5b-8; D003165:Complement System Proteins