Cytochrome caa3 from the thermophilic bacterium Thermus thermophilus: a member of the heme-copper oxidase superfamily.

The subject of this short review is the cytochrome c oxidase (caa3) from the thermophilic bacterium Thermus thermophilus. First, some of the extensive physical and enzymological results obtained with this enzyme are reviewed, and two experiments are described, involving isotope substitutions in combination with Mössbauer and ENDOR spectroscopies, which have provided novel insight into the active sites of the enzyme. Second, we summarize recent molecular genetic work showing that Thermus cytochrome caa3 is a bona fide member of the superfamily of heme-copper oxidases. Finally, we present a rough three-dimensional model and speculate about certain features of the metal-binding sites.