Nature of the metal ion requirement for assembly and function of the first component of human complement.

摘要: Abstract The first component of human complement (C1) was reconstituted from equimolar concentrations its purified subunits C1q, C1r, and C1s, in the presence each nine different metal ions for purpose studying qualitative quantitative nature ion requirement C1 assembly function. For with ion, three assays characteristic were performed as follows: (1) spontaneous activation absence regulatory protein C1-inhibitor assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis simultaneously quantifying specific proteolysis C1r C1s subunits; (2) induced aggregated IgG inhibitor similarly analyzed electrophoresis; (3) formation 16 S macromolecular determined analytical ultracentrifuge. all experiments, trace contaminants removed buffers proteins. All divalent cations tested transition period periodic table (i.e. Ca2+, Mn2+, Co2+, Ni2+, Zn2+) effectively mediated functional C1. Dose curves showed maximal at 30 to 50 microM above ions. However, when increased microM, became inhibited. further right table, better ion. Competition experiments indicated that binding sites mediating inhibition are distinct those promoting activation. Other also function Cd2+ Tb3+; however, Mg2+ Ba2+ ineffective. promoted C2 consumption normal serum treated IgG. In conclusion, can be numerous direct opposition accepted theory, there is no calcium.