Enzyme inhibitors antimycin

In 2003, the Di Xia group published an X-ray crystallographic study of substrate and inhibitor molecules at the Qo and Qi site. They intended to compare the structure of the native enzyme (PDB INTM) with the cytochrome bci complex having substrate or inhibitors in the Qo and/or Qi sites. The complex with substrate ubiquinone UQ2 (PDB INTZ) was discussed previously in this section. The complex with the inhibitor antimycin Ai (PDB INTK) will be discussed here. A fourth complex with the ubiquinone-model... 

The superoxide free radical thus generated, 02, is very reactive and can damage enzymes, membrane lipids, and nucleic acids. Antimycin A, an inhibitor of Complex 111, may act by occupying the Q, site (Fig. 19-11), thus blocking the Q cycle and prolonging the binding of Q to the Qp site this would increase the likelihood of superoxide radical formation and cellular damage. From... 

The half-saturation of the system with cytochrome c was achieved at a concentration of about 10 M (Fig. 15a, b). In all cases, the effect was reversed and prevented by antimycin - an inhibitor of the succinate-cytochrome c reductase activity of this enzyme complex - but was not suppressed by cyanide. In concluding this series of experiments, we investigated the isolated NADH-CoQ reductase complex of the respiratory chain of mitochondria. As can be seen from the results given in Fig. 16, an increase in the concentration of the enzyme complex was accompanied by an increase in the negative charge of the octane phase. 

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