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Diuba AV, Vygodina TV, Azarkina NV, Arutyunyan AM, Soulimane T, Vos MH, Konstantinov AA. Individual heme a and heme a 3 contributions to the Soret absorption spectrum of the reduced bovine cytochrome c oxidase. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2023; 1864:148937. [PMID: 36403793 DOI: 10.1016/j.bbabio.2022.148937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 10/24/2022] [Accepted: 11/11/2022] [Indexed: 11/19/2022]
Abstract
Bovine cytochrome c oxidase (CcO) contains two hemes, a and a3, chemically identical but differing in coordination and spin state. The Soret absorption band of reduced aa3-type cytochrome c oxidase consists of overlapping bands of the hemes a2+ and a32+. It shows a peak at ∼444 nm and a distinct shoulder at ∼425 nm. However, attribution of individual spectral lineshapes to hemes a2+ and a32+ in the Soret is controversial. In the present work, we characterized spectral contributions of hemes a2+ and a32+ using two approaches. First, we reconstructed bovine CcO heme a2+ spectrum using a selective Ca2+-induced spectral shift of the heme a2+. Second, we investigated photobleaching of the reduced Thermus thermophilus ba3- and bovine aa3-oxidases in the Soret induced by femtosecond laser pulses in the Q-band. The resolved spectra show splitting of the electronic B0x-, B0y-transitions of both reduced hemes. The heme a2+ spectrum is shifted to the red relative to heme a32+ spectrum. The ∼425 nm shoulder is mostly attributed to heme a32+.
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Affiliation(s)
- Artem V Diuba
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory 1, Bld.40, Moscow 119992, Russia.
| | - Tatiana V Vygodina
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory 1, Bld.40, Moscow 119992, Russia.
| | - Natalia V Azarkina
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory 1, Bld.40, Moscow 119992, Russia.
| | - Alexander M Arutyunyan
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory 1, Bld.40, Moscow 119992, Russia.
| | - Tewfik Soulimane
- Materials and Surface Science Institute, University of Limerick, V94 T9PX, Ireland.
| | - Marten H Vos
- LOB, CNRS, INSERM, Ecole Polytechnique, Institut Polytechnique de Paris, Palaiseau 91120, France.
| | - Alexander A Konstantinov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory 1, Bld.40, Moscow 119992, Russia
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