Tryptophan to Tryptophan Hole Hopping in an Azurin Construct

0582015 - ÚFCH JH 2024 RIV US eng J - Journal Article
Melčák, Martin - Šebesta, Filip - Heyda, Jan - Gray, H. B. - Záliš, Stanislav - Vlček, Antonín
Tryptophan to Tryptophan Hole Hopping in an Azurin Construct.
Journal of Physical Chemistry B. Roč. 128, č. 1 (2023), s. 96-108. ISSN 1520-6106. E-ISSN 1520-5207
R&D Projects: GA ČR(CZ) GA21-05180S; GA MŠMT(CZ) LTAUSA18026
Research Infrastructure: e-INFRA CZ II - 90254
Institutional support: RVO:61388955
Keywords : accelerated electron flow * density-functional theory * relaxation dynamics * charge-transfer * photolyase * proteins * cryptochromes * transport
OECD category: Physical chemistry
Impact factor: 3.3, year: 2022
Method of publishing: Open access

Electron transfer (ET) between neutral and cationic tryptophan residues in the azurin construct [Re-I(H126)(CO)(3)(dmp)](W124)(W122)Cu-I (dmp = 4,7-Me-2-1,10-phenanthroline) was investigated by Born-Oppenheimer quantum-mechanics/molecular mechanics/molecular dynamics (QM/MM/MD) simulations. We focused on W124(center dot+) <- W122 ET, which is the middle step of the photochemical hole-hopping process *Re-II(CO)(3)(dmp(center dot-)) <- W124 <- W122 <- Cu-I, where sequential hopping amounts to nearly 10,000-fold acceleration over single-step tunneling (ACS Cent. Sci. 2019, 5, 192-200). In accordance with experiments, UKS-DFT QM/MM/MD simulations identified forward and reverse steps of W124(center dot+) - W122 ET equilibrium, as well as back ET Re-I(CO)(3)(dmp(center dot-))> W124(center dot+) that restores *Re-II(CO)(3)(dmp(center dot-)). Strong electronic coupling between the two indoles (>= 40 meV in the crossing region) makes the productive W124(center dot+) <- W122 ET adiabatic. Energies of the two redox states are driven to degeneracy by fluctuations of the electrostatic potential at the two indoles, mainly caused by water solvation, with contributions from the protein dynamics in the W122 vicinity. ET probability depends on the orientation of Re(CO)(3)(dmp) relative to W124 and its rotation diminishes the hopping yield. Comparison with hole hopping in natural systems reveals structural and dynamics factors that are important for designing efficient hole-hopping processes.
Permanent Link: https://hdl.handle.net/11104/0350145