TY - JOUR
T1 - Kinetics and energetics of intramolecular electron transfer in single‐point labeled tups‐cytochrome c derivatives
AU - Khoroshyy, Petro
AU - Tenger, Katalin
AU - Chertkova, Rita V.
AU - Bocharova, Olga V.
AU - Kirpichnikov, Mikhail P.
AU - Borovok, Natalia
AU - Groma, Géza I.
AU - Dolgikh, Dmitry A.
AU - Kotlyar, Alexander B.
AU - Zimányi, László
N1 - Publisher Copyright:
© 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
PY - 2021/11/1
Y1 - 2021/11/1
N2 - Electron transfer within and between proteins is a fundamental biological phenomenon, in which efficiency depends on several physical parameters. We have engineered a number of horse heart cytochrome c single‐point mutants with cysteine substitutions at various positions of the protein surface. To these cysteines, as well as to several native lysine side chains, the photoinduced redox label 8‐thiouredopyrene‐1,3,6‐trisulfonate (TUPS) was covalently attached. The long‐lived, low potential triplet excited state of TUPS, generated with high quantum efficiency, serves as an electron donor to the oxidized heme c. The rates of the forward (from the label to the heme) and the reverse (from the reduced heme back to the oxidized label) electron transfer reactions were obtained from multichannel and single wavelength flash photolysis absorption kinetic experiments. The electronic coupling term and the reorganization energy for electron transfer in this system were estimated from temperature‐dependent experiments and compared with calculated parameters using the crystal and the solution NMR structure of the protein. These results together with the observation of multiexponential kinetics strongly support earlier conclusions that the flexible arm connecting TUPS to the protein allows several shortcut routes for the electron involving through space jumps between the label and the protein surface.
AB - Electron transfer within and between proteins is a fundamental biological phenomenon, in which efficiency depends on several physical parameters. We have engineered a number of horse heart cytochrome c single‐point mutants with cysteine substitutions at various positions of the protein surface. To these cysteines, as well as to several native lysine side chains, the photoinduced redox label 8‐thiouredopyrene‐1,3,6‐trisulfonate (TUPS) was covalently attached. The long‐lived, low potential triplet excited state of TUPS, generated with high quantum efficiency, serves as an electron donor to the oxidized heme c. The rates of the forward (from the label to the heme) and the reverse (from the reduced heme back to the oxidized label) electron transfer reactions were obtained from multichannel and single wavelength flash photolysis absorption kinetic experiments. The electronic coupling term and the reorganization energy for electron transfer in this system were estimated from temperature‐dependent experiments and compared with calculated parameters using the crystal and the solution NMR structure of the protein. These results together with the observation of multiexponential kinetics strongly support earlier conclusions that the flexible arm connecting TUPS to the protein allows several shortcut routes for the electron involving through space jumps between the label and the protein surface.
KW - Cytochrome c
KW - Intramolecular electron transfer
KW - TUPS
KW - Time‐resolved spectroscopy
KW - Triplet excited state
UR - http://www.scopus.com/inward/record.url?scp=85119915851&partnerID=8YFLogxK
U2 - 10.3390/molecules26226976
DO - 10.3390/molecules26226976
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C2 - 34834068
AN - SCOPUS:85119915851
SN - 1420-3049
VL - 26
JO - Molecules
JF - Molecules
IS - 22
M1 - 6976
ER -