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Time‐resolved resonance Raman study on ultrafast structural relaxation and vibrational cooling of photodissociated carbonmonoxy myoglobin
Author(s) -
Kitagawa Teizo,
Haruta Nami,
Mizutani Yasuhisa
Publication year - 2002
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.10096
Subject(s) - chemistry , myoglobin , photodissociation , heme , protein dynamics , carbon monoxide , raman spectroscopy , resonance raman spectroscopy , hemeprotein , dissociation (chemistry) , resonance (particle physics) , excited state , relaxation (psychology) , photochemistry , flash photolysis , vibrational energy relaxation , picosecond , molecular dynamics , kinetics , reaction rate constant , molecule , computational chemistry , laser , atomic physics , enzyme , optics , psychology , social psychology , biochemistry , quantum mechanics , catalysis , physics , organic chemistry
A localized small structural change is converted to a higher order conformational change of protein and extends to a mesoscopic scale to induce a physiological function. To understand such features of protein, ultrafast dynamics of myoglobin (Mb) following photolysis of carbon monoxide were investigated. Recent results are summarized here with a stress on structural and vibrational energy relaxation. The core expansion of heme takes place within 2 ps but the out of plane displacement of the heme iron and the accompanying protein conformational change occur in 10 and 100 s of the picosecond regimes, respectively. Unexpectedly, it was found from UV resonance Raman spectra that Trp7 in the N‐terminal region and Tyr151 in the C‐terminal region undergo appreciable structural changes upon ligand binding–dissociation while Tyr104, Tyr146, and Trp14 do not. Because of the communication between the movements of these surface residues and the heme iron, the rate of spectral change of the iron‐histidine (Fe‐ His) stretching band after CO photodissociation is influenced by the viscosity of solvent. Temporal changes of the anti‐Stokes Raman intensity demonstrated immediate generation of vibrationally excited heme upon photodissociation and its decay with a time constant of 1–2 ps. © 2002 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy) 67: 207–213, 2002