Abstract New experimental evidence that a switch controls the reduction of the heme a3－CuB binuclear centre has been observed in the N2-dried thin film of purified cytochrome oxidase. When immersing the enzyme film into the acid phosphate buffer with extremely low concentration of dithionite, a spectrum was given to show a reduction of heme a with no electrons resting on CuA. By increasing dithionite, electrons could be accumulated gradually on CuA, but the binuclear centre still remains in the oxidized state. When the accumulation of electrons on CuA and/or heme a exceeded a threshold, a turnover of reduction of the binuclear centre and oxidation of heme a occurred abruptly. This switch-like action is pH-dependent.
Received: 11 July 2001
Revised: 28 December 2001
Accepted manuscript online:
PACS:
82.39.Jn
(Charge (electron, proton) transfer in biological systems)
Fund: Project supported by the National Natural Science Foundation of China (Grant No 39900029).
Cite this article:
Wang Ao-Jin (王敖金), Xu Jian-Xing (徐建兴) A switch in the electron transfer from heme a to binuclear centre of cytochrome c oxidase 2002 Chinese Physics 11 506
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