A single catalytic site model is proposed to account for the multiphasic kinetics of oxidation of ferrocytochrome c by cytochrome c oxidase (ferrocytochrome c:oxygen oxidoreductase, EC 1.9.3.1). This model involves nonproductive binding of substrate to sites near the catalytic site on cytochrome c oxidase for cytochrome c, decreasing the binding constant for cytochrome c at the catalytic site. ...

The cytochrome c oxidase (COX) is the terminal enzyme of the respiratory chain. The complex accepts electrons from cytochrome c and passes them onto molecular oxygen. This process contributes to energy capture in the form of a membrane potential across the inner membrane. The enzyme complex assembles in a stepwise process from the three mitochondria-encoded core subunits Cox1, Cox2 and Cox3, wh...

In the preceding paper the oxidation of substrates by “indophenol oxidase” was demonstrated to be a joint action of cytochrome and cytochrome oxidase. It was further shown that with a given amount of oxidase the velocity of hydroquinone oxidation reached a maximum as the amount of added cytochrome was increased. The latter fact immediately suggested the probability that the rapid aerobic oxidat...

The biogenesis of multimeric protein complexes of the inner mitochondrial membrane in yeast requires a number of nuclear-coded ancillary proteins. One of these, Pet100p, is required for cytochrome c oxidase. Previous studies have shown that Pet100p is not required for the synthesis, processing, or targeting of cytochrome c oxidase subunits to the mitochondrion nor for heme A biosynthesis. Here,...

Mitochondrial cytochrome c oxidase utilizes electrons provided by cytochrome c for the active vectorial transport of protons across the inner mitochondrial membrane through the reduction of molecular oxygen to water. Direct structural evidence on the transient cytochrome c oxidase-cytochrome c complex thus far, however, remains elusive and its physiological relevant oligomeric form is unclear. ...

We purified membrane-bound cytochrome c-550 [cytochrome c-550(m)] to an electrophoretically homogeneous state from Nitrobacter winogradskyi. The cytochrome showed peaks at 409 and 525 nm in the oxidized form and peaks at 416, 521, and 550 nm in the reduced form. The molecular weight of the cytochrome was estimated to be 18,400 on the basis of protein and heme c contents and 18,600 by gel filtra...

The aerobic respiratory chain of Pyrobaculum oguniense is expressed constitutively even under anaerobic conditions. The membranes of both aerobically and anaerobically grown cells show oxygen consumption activity with NADH as substrate, bovine cytochrome c oxidase activity and TMPD oxidase activity. Spectroscopic analysis and haem analysis of membranes of aerobically grown cells show the presen...

The iron-oxidizing bacterium Acidithiobacillus ferrooxidans MON-1 is highly resistant not only to mercuric chloride (HgCl(2)) but also to organomercurials such as methylmercury chloride (MMC). We have found that cytochrome c oxidase, purified from strain MON-1, reduces Hg(2+) to volatilizable metal mercury (Hg(0)) with reduced mammalian cytochrome c or Fe(2+) as an electron donor. In this study...

Cytochrome c oxidase (EC 1.9.3.1) is the terminal enzyme of the mitochondria respiratory chain catalysing electron transfer from cytochrome c to molecular oxygen [ 1,2]. The molecular mechanism of this process is still not understood. At present, little is known about such important structural features as the position of the prosthetic groups or the location and characteristics of the cytochrom...