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Relaxation Dynamics of Pseudomonas aeruginosa Re^I(C)O_3(α-diimine)(HisX)^+ (X=83, 107, 109, 124, 126)Cu-^(II) Azurins

Blanco-Rodríguez, Ana María and Busby, Michael and Ronayne, Kate and Towrie, Michael and Grădinaru, Cristian and Sudhamsu, Jawahar and Sýkora, Jan and Hof, Martin and Záliš, Stanislav and Di Bilio, Angel J. and Crane, Brian R. and Gray, Harry B. and Vlček, Antonín, Jr. (2009) Relaxation Dynamics of Pseudomonas aeruginosa Re^I(C)O_3(α-diimine)(HisX)^+ (X=83, 107, 109, 124, 126)Cu-^(II) Azurins. Journal of the American Chemical Society, 131 (33). pp. 11788-11800. ISSN 0002-7863.

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Photoinduced relaxation processes of five structurally characterized Pseudomonas aeruginosa Re^I(CO)_3(α-diimine)(HisX) (X = 83, 107, 109, 124, 126)Cu^(II) azurins have been investigated by time-resolved (ps−ns) IR spectroscopy and emission spectroscopy. Crystal structures reveal the presence of Re-azurin dimers and trimers that in two cases (X = 107, 124) involve van der Waals interactions between interdigitated diimine aromatic rings. Time-dependent emission anisotropy measurements confirm that the proteins aggregate in mM solutions (D2O, KPi buffer, pD = 7.1). Excited-state DFT calculations show that extensive charge redistribution in the ReI(CO)_3 → diimine ^3MLCT state occurs: excitation of this ^3MLCT state triggers several relaxation processes in Re-azurins whose kinetics strongly depend on the location of the metallolabel on the protein surface. Relaxation is manifested by dynamic blue shifts of excited-state ν(CO) IR bands that occur with triexponential kinetics: intramolecular vibrational redistribution together with vibrational and solvent relaxation give rise to subps, 2, and 8−20 ps components, while the ~10^2 ps kinetics are attributed to displacement (reorientation) of the Re^I(CO)_3(phen)(im) unit relative to the peptide chain, which optimizes Coulombic interactions of the Re^I excited-state electron density with solvated peptide groups. Evidence also suggests that additional segmental movements of Re-bearing β-strands occur without perturbing the reaction field or interactions with the peptide. Our work demonstrates that time-resolved IR spectroscopy and emission anisotropy of Re^I carbonyl−diimine complexes are powerful probes of molecular dynamics at or around the surfaces of proteins and protein−protein interfacial regions.

Item Type:Article
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URLURL TypeDescription
Sýkora, Jan0000-0003-0936-9368
Hof, Martin0000-0003-2884-3037
Gray, Harry B.0000-0002-7937-7876
Additional Information:Copyright © 2009 American Chemical Society. Received April 10, 2009; Publication Date (Web): July 29, 2009. This work was supported by EPSRC (EP/E060544), STFC (CMSD43), COST D35, Ministry of Education of the Czech Republic (OC09043 and LC06063), NSF (CHE-0802907 and CHE-0749997), and NIH (DK019038). Supporting Information: Tables of experimentally determined orientation of the histidine imidazole ligand relative to the Re(CO)_3(phen) unit in the five proteins, DFT-calculated frontier Kohn−Sham orbitals and electronic transitions of Re(Etim) in two conformations, comparison of calculated and experimental ground- and excited-state ν(CO) IR wavenumbers of Re(Etim), and results of stretched-exponential fitting of the A′(1) ν(CO) band shift kinetics at different concentrations. Figures of DFT-calculated structures of Re(Etim) in several ground- and excited-state conformations and time traces of the peak energy of the A′(1) ν(CO) band of 107-dmp, 124-phen, and 126-phen measured at different concentrations. Full text of ref 33 (Gaussian 03 software) is provided. This material is available free of charge via the Internet at
Group:CCI Solar Fuels
Funding AgencyGrant Number
Engineering and Physical Sciences Research CouncilEP/E060544
Science and Technology Facilities CouncilCMSD43
Engineering and Physical Sciences Research CouncilCOST D35
Ministry of Education of the Czech RepublicOC09043
Ministry of Education of the Czech RepublicLC06063
Issue or Number:33
Record Number:CaltechAUTHORS:20090911-153601363
Persistent URL:
Official Citation:Relaxation Dynamics of Pseudomonas aeruginosa ReI(CO)3(α-diimine)(HisX)+ (X = 83, 107, 109, 124, 126)CuII Azurins Ana Mara Blanco-Rodrguez, Michael Busby, Kate Ronayne, Michael Towrie, Cristian Grdinaru, Jawahar Sudhamsu, Jan Skora, Martin Hof, Stanislav Zli, Angel J. Di Bilio, Brian R. Crane, Harry B. Gray, Antonn Vlek Jr. Journal of the American Chemical Society 2009 131 (33), 11788-11800
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:15805
Deposited By: George Porter
Deposited On:07 Oct 2009 21:35
Last Modified:09 Mar 2020 13:19

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