ISSN:
1420-9071
Keywords:
Key words. Mitochondrial particles; cytochrome oxidase; fast and slow conformation; cyanide binding; nucleotides; cholate; structure.
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Abstract. We determined the fraction of ‘slow’ and ‘fast’ conformations of bovine cytochrome c oxidase, following the kinetics of cyanide binding to the oxidized enzyme. We investigated whether treatment of heart mitochondrial particles with different commercially available types of cholate (standard and ultra-pure) can affect the fraction of cytochrome c oxidase in the two states. Compared to standard cholate, the use of ultra-pure cholate for solubilization of heart mitochondrial particles significantly increased the fraction of the fast enzyme. Complete homogeneity (∼100% fast) was observed when cytochrome c oxidase was solubilized with ultra-pure cholate from heart mitochondrial particles pre-equilibrated with AMP; equilibration with ADP yielded a much smaller fraction of fast enzyme (∼35%). These observations are discussed on the basis of the structural relationships between the known cholate-binding site and the binuclear cytochrome a3-CuB site: variation in the occupancy of this binding site with cholate or nucleotides may modify reactivity of the oxidized binuclear centre towards cyanide.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/PL00000631
Permalink
