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This article is cited in 1 scientific paper (total in 1 paper)
Biophotonics
Femtosecond absorption spectroscopy of reduced and oxidized forms of cytochrome c oxidase: excited states and relaxation processes in heme $a$ and $a_3$ centers
I. V. Shelaeva, F. E. Gosteva, T. V. Vygodinab, S. V. Lepeshkevichc, B. M. Dzhagarovc a Semenov Institute of Chemical Physics, Russian Academy of Sciences, 119991, Moscow, Russia
b Belozerski Institute of Physicochemical Biology, Moscow State University, 119991, Moscow, Russia
c Stepanov Institute of Physics, National Academy of Sciences of Belarus, 220072, Minsk, Belarus
Abstract:
Excited electronic states and intraheme relaxation processes in the oxidized and reduced forms of mitochondrial cytochrome c oxidase extracted from a beef heart have been investigated by femtosecond absorption spectroscopy. The spectral and kinetic characteristics of short-lived intermediates have been measured from 80 fs to 20 ps after the photoexcitation. It is found that nonradiative electronic relaxation of the excitation energy in heme $a$, both in the oxidized (Fe(III)$a$) and reduced (Fe(II)$a$) forms, occurs successively as three processes, after the end of which heme $a$ is in the ground state with a large store of vibrational energy. The subsequent vibrational relaxation (heme cooling) lasts for several picoseconds. It is found for reduced heme $a_3$ (Fe(II) $a_3$) that the electronic relaxation occurs as a result of two successive stages, which changes to vibrational relaxation in the ground state. The mechanism and dynamics of electronic excitation energy conversion in cytochrome c oxidase are analyzed.
Keywords:
cytochrome c oxidase, femtosecond absorption spectroscopy, excited electronic states, relaxation processes, spectral intermediates.
Received: 13.03.2019 Revised: 13.03.2019 Accepted: 11.06.2019
Citation:
I. V. Shelaev, F. E. Gostev, T. V. Vygodina, S. V. Lepeshkevich, B. M. Dzhagarov, “Femtosecond absorption spectroscopy of reduced and oxidized forms of cytochrome c oxidase: excited states and relaxation processes in heme $a$ and $a_3$ centers”, Optics and Spectroscopy, 127:4 (2019), 697–703; Optics and Spectroscopy, 127:4 (2019), 756–762
Linking options:
https://www.mathnet.ru/eng/os598 https://www.mathnet.ru/eng/os/v127/i4/p697
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