Inhibition of the Third Component of the Complement System by Derivatives of Aromatic Amino Acids

作者：Ross S. Basch · 发表于：The Journal of Immunology · 年份：1965 · DOI：10.4049/jimmunol.94.4.629 · 被引用次数：25 · 研究领域：Complement system in diseases、Monoclonal and Polyclonal Antibodies Research、HIV Research and Treatment

Summary It is clear that a wide variety of aromatic organic compounds, including the derivatives of the aromatic amino acids, are capable of inhibiting the cation independent phase of complement action. The activity of the compounds tested was not completely restricted to a single step. Both the formation of the IA reactive cell and its subsequent stabilization were affected. However, the kinetic flow data, the static inhibition tests and the similarity of the structural requirements for inhibition of the specific step with the requirements for the inhibition of the whole system all lead to the conclusion that the primary site of action is at the formation of the thermostable intermediate. The mechanism of this inhibition is less clear. The pattern of inhibition produced by the various analogs suggests the inhibition of a proteolytic enzyme. The step inhibited is extremely sensitive to changes in temperature. This also suggests an enzymatic mechanism. The kinetic data presented in Figures 7 and 8, although not providing direct proof, are compatible with the idea that a component in the heated guinea pig serum is a substrate in an enzymatic reaction. Furthermore, the data obtained in the presence of acetyl-L-tyrosine indicate that this compound, and presumably the other aromatic ring containing compounds, are acting as competitive inhibitors. The simplest explanation for these observations is that some component present in the EAC′1,4,2,3c complex is an enzyme, presumably prot...