Identification of the discontinuous epitope in human complement protein C9 recognized by anti-melittin antibodies.

摘要: Polyclonal rabbit antibodies against melittin recognize human C protein C9 and retard C9-mediated hemolysis. Human contains a tetrameric pentameric sequence (amino acids 293-296 528-532, respectively) that together match continuous segment in the sequence, i.e., residues 8-16. It has been suggested regions on form discontinuous epitope folded mimics structure of melittin. To further test this hypothesis, to C9-sequence-specific peptides were prepared. Peptides containing either homologous or with short stretches respective amino- carboxyl-terminal flanking synthesized, as well composite peptide predicted resemble linear, nine-amino acid sequence. Direct competitive binding assays demonstrated sequences are part is recognized by anti-melittin IgG. However, only directed complete capable inhibiting Because neither anti-tetramer nor anti-pentamer affect hemolysis whereas anti-composite do, we propose changes conformation around hinge located between 296 528 latter two inhibit unfolding required for membrane insertion subsequent