title: Relaxation dynamics of Pseudomonas aeruginosa Re(I)(CO)3(alpha-diimine)(HisX)+ (X = 83, 107, 109, 124, 126)Cu(II) azurins.
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.
authors.affiliation: School of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, United Kingdom.
authors.forename: Ana María
authors.initials: AM
authors.lastname: Blanco-Rodríguez
authors.forename: Michael
authors.initials: M
authors.lastname: Busby
authors.forename: Kate
authors.initials: K
authors.lastname: Ronayne
authors.forename: Michael
authors.initials: M
authors.lastname: Towrie
authors.forename: Cristian
authors.initials: C
authors.lastname: Grădinaru
authors.forename: Jawahar
authors.initials: J
authors.lastname: Sudhamsu
authors.forename: Jan
authors.initials: J
authors.lastname: Sýkora
authors.forename: Martin
authors.initials: M
authors.lastname: Hof
authors.forename: Stanislav
authors.initials: S
authors.lastname: Zális
authors.forename: Angel J
authors.initials: AJ
authors.lastname: Di Bilio
authors.forename: Brian R
authors.initials: BR
authors.lastname: Crane
authors.forename: Harry B
authors.initials: HB
authors.lastname: Gray
authors.forename: Antonín
authors.initials: A
authors.lastname: Vlcek
mesh_terms: D000042:Absorption; D016880:Anisotropy; D001400:Azurin / Q000737:chemistry / Q000378:metabolism*; D001665:Binding Sites; D004579:Electron Transport; D004583:Electrons; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000378:metabolism*; D011487:Protein Conformation; D011550:Pseudomonas aeruginosa; D011789:Quantum Theory; D012211:Rhenium / Q000378:metabolism; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D013997:Time Factors
chemical_list: D009942:Organometallic Compounds; D001400:Azurin; D012211:Rhenium