Spectral shifts of cytochrome c oxidase induced by complexons.
Ca2+-chelating agents, such as EDTA and ATP, are shown to bring about a rapid spectral response of the oxidized cytochrome c oxidase due to reversal of the Ca2+-induced red shift of the gamma- and alpha-absorption bands of the ferric enzyme. In addition, complexons are found to bring about Ca2+-independent, slow irreversible spectral changes indicative of a conformational transition of cytochrome oxidase. 1 mol EDTA per mol enzyme is sufficient to produce the maximal effect even in the presence of excess Ca2+, indicating high specificity of interaction. It is suggested that the conformation of cytochrome c oxidase may be regulated by the tightly bound "non-redox' metal ions (Mg, Zn, Cux) known to be present in the enzyme. These ions might be involved in specific binding of physiological effectors with chelating properties, such as ATP.
Konstantinov
A
A
A.N. Belozersky Laboratory of Molecular Biology and Bioorganic Chemistry, Moscow State University, USSR.
Vygodina
T
T
Popova
E
E
Berka
V
V
Musatov
A
A
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002417:Cattle; D002614:Chelating Agents / Q000494:pharmacology*; D004492:Edetic Acid / Q000494:pharmacology; D003576:Electron Transport Complex IV; D008929:Mitochondria, Heart / Q000201:enzymology*; D010618:Phenanthrolines / Q000494:pharmacology; D011487:Protein Conformation / Q000187:drug effects; D013053:Spectrophotometry
D002614:Chelating Agents; D010618:Phenanthrolines; D000255:Adenosine Triphosphate; D004492:Edetic Acid; D003576:Electron Transport Complex IV; D002118:Calcium; C025205:1,10-phenanthroline