title: Influence of aromatic compounds on the interaction of activated C4 with EAC1.
abstract: The influence of amino acids and their derivatives on the formation of SAC14 from SAC1 and C4 were investigated. Among the compounds tested, aromatic amino acids containing phenolic hydroxyl group or carbobenzoxyl group inhibited the formation of SAC14. When aromatic compounds other than amino acids were tested, the inhibitory capacities of these compounds were found to relate to the substituent group incorporated in the aromatic ring. Aromatic compounds with subsituent groups with negative Hammett's substituent constant showed stronger inhibition. Conversely, compounds with group with positive constant showed weaker inhibition. These results may suggest that the increased electron density in the aromatic ring is responsible for the inhibition. Regardless of inhibition of SAC14 formation, these inhibitors did not affect the enzymatic action of EAC1 or C1 on C4 but inhibited the binding of activated C4 to EAC1.
mesh_terms: D000372:Agglutination Tests; D000596:Amino Acids / Q000494:pharmacology*; D000906:Antibodies; D003181:Complement C4 / Q000378:metabolism*; D003165:Complement System Proteins / Q000378:metabolism*; D004912:Erythrocytes / Q000276:immunology*; D010636:Phenols / Q000494:pharmacology
chemical_list: D000596:Amino Acids; D000906:Antibodies; D003181:Complement C4; D010636:Phenols; D003165:Complement System Proteins