Relaxation Dynamics of Pseudomonas aeruginosa ReI(CO)₃(α-diimine)(HisX)+ (X = 83, 107, 109, 124, 126)CuII Azurins

Citations Over TimeTop 13% of 2009 papers

Abstract

Photoinduced relaxation processes of five structurally characterized Pseudomonas aeruginosa Re(I)(CO)(3)(alpha-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 (D(2)O, KP(i) buffer, pD = 7.1). Excited-state DFT calculations show that extensive charge redistribution in the Re(I)(CO)(3) --> diimine (3)MLCT state occurs: excitation of this (3)MLCT 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 nu(CO) IR bands that occur with triexponential kinetics: intramolecular vibrational redistribution together with vibrational and solvent relaxation give rise to subps, approximately 2, and 8-20 ps components, while the approximately 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 beta-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.

Related Papers

• → Highlights of the spectroscopy, photochemistry and electrochemistry of [M(CO)4(α-diimine)] complexes, M=Cr, Mo, W(2002)150 cited
• → Dipyridocatecholate-Bridged Complexes of Platinum and Ruthenium Diimine Chromophores(1998)44 cited
• → Synthesis, characterization, electrochemistry and photophysical studies of rhenium(I) tricarbonyl diimine complexes with carboxaldehyde alkynyl ligands(2014)18 cited
• → Synthesis and characterization of tris(heteroleptic) diimine complexes of chromium(III)(2007)19 cited
• → Synthesis and characterization of cationic rhodium(I) dicarbonyl complexes(2010)6 cited