Publication Date:
2015-12-02
Description:
Publication date: Available online 1 December 2015 Source: FEBS Letters Author(s): Artem V. Dyuba, Tatiana Vygodina, Natalia Azarkina, Alexander A. Konstantinov The effect of Ca 2+ on the rate of heme a reduction by dithionite and hexaammineruthenium (RuAm) was studied in the cyanide-complexed bovine cytochrome oxidase (CcO). The rate of heme a reduction is proportional to RuAm concentration below 300 μM with k v of 0.53 × 10 6 M −1 s −1 . Ca 2+ inhibits the rate of heme a reduction by dithionite by ∼25%. As the reaction speeds up with increased concentrations of RuAm, the inhibition by Ca 2+ disappears. The inhibition of heme a reduction may contribute to recently described partial inhibition of CcO by Ca 2+ in the enzymatic assays. The inhibitory effect of Ca 2+ on heme a reduction indicates that ET through heme a may be coupled to proton movement in the exit part of the proton channel H.
Print ISSN:
0014-5793
Electronic ISSN:
1873-3468
Topics:
Biology
,
Chemistry and Pharmacology
,
Physics
