Limited proteolysis of complement components C2 and factor B. Structural analogy and limited sequence homology.

摘要: A method is described for the simultaneous purification of milligram quantities complement components C2 and Factor B. Both products are homogeneous by criteria polyacrylamide-gel electrophoresis N-terminal sequence analysis. Component cleaved serine proteinase C1s at an X-Lys bond to give fragment C2a (approx. mol.wt. 74000) C2b 34000). The two fragments can be separated gel filtration without need reducing or denaturing agents. Fragment represents end molecule. Similar results were seen on cleavage B D in presence component C3. Again non-covalently linked formed. smaller, Ba 36,000),) has threonine as residue, does B; larger, Bb mol. wt. 58000), lysine residue. similar pattern obtained limited proteolysis trypsin, suggesting Arg-Lys-or Lys-Lys point cleavage. Although show no apparent homology, a degree homology around sites proteolytic