Back to Search
Start Over
Redox-induced structural dynamics of Fe-heme ligand in myoglobin by X-ray absorption spectroscopy.
- Source :
-
Biophysical journal [Biophys J] 2003 Jul; Vol. 85 (1), pp. 549-58. - Publication Year :
- 2003
-
Abstract
- The Fe(III) --> Fe(II) reduction of the heme iron in aquomet-myoglobin, induced by x-rays at cryogenics temperatures, produces a thermally trapped nonequilibrium state in which a water molecule is still bound to the iron. Water dissociates at T > 160 K, when the protein can relax toward its new equilibrium, deoxy form. Synchrotron radiation x-ray absorption spectroscopy provides information on both the redox state and the Fe-heme structure. Owing to the development of a novel method to analyze the low-energy region of x-ray absorption spectroscopy, we obtain structural pictures of this photo-inducible, irreversible process, with 0.02-0.06-A accuracy, on the protein in solution as well as in crystal. After photo-reduction, the iron-proximal histidine bond is shortened by 0.15 A, a reinforcement that should destabilize the iron in-plane position favoring water dissociation. Moreover, we are able to get the distance of the water molecule even after dissociation from the iron, with a 0.16-A statistical error.
- Subjects :
- Computer Simulation
Crystallography methods
Energy Transfer
Heme radiation effects
Iron radiation effects
Ligands
Oxidation-Reduction
Protein Conformation
Absorptiometry, Photon methods
Heme chemistry
Iron chemistry
Models, Molecular
Myoglobin chemistry
Myoglobin radiation effects
Spectrometry, X-Ray Emission methods
Water chemistry
Subjects
Details
- Language :
- English
- ISSN :
- 0006-3495
- Volume :
- 85
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- Biophysical journal
- Publication Type :
- Academic Journal
- Accession number :
- 12829509
- Full Text :
- https://doi.org/10.1016/S0006-3495(03)74499-3