Molecular dynamics simulation of photodissociation of carbon monoxide from hemoglobin
A molecular dynamics simulation of the photodissociation of carbon monoxide from the alpha subunit of hemoglobin is described. To initiate photodissociation, trajectories of the liganded molecule were interrupted, the iron-carbon monoxide bond was broken, and the parameters of the iron-nitrogen bonds were simultaneously altered to produce a deoxyheme conformation. Heme potential functions were used that reproduce the energies and forces for the iron out-of-plane motion obtained from quantum mechanical calculations. The effect of the protein on the rate and extent of the displacement of the iron from the porphyrin plane was assessed by comparing the results with those obtained for an isolated complex of heme with imidazole and carbon monoxide. The half-time for the displacement of the iron from the porphyrin plane was found to be 50-150 fs for both the protein and the isolated complex. These results support the interpretation of optical absorption studies using 250-fs laser pulses that the iron is displaced from the porphyrin plane within 350 fs in both hemoglobin and a free heme complex in solution.
- Research Organization:
- National Institute of Arthritis, Bethesda, MD
- OSTI ID:
- 5646587
- Journal Information:
- Proc. Natl. Acad. Sci. U.S.A.; (United States), Vol. 82:7
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CARBON MONOXIDE
DISSOCIATION
HEMOGLOBIN
DISSOCIATION ENERGY
HEME
IRON
MAN
PHOTOLYSIS
SIMULATION
ANIMALS
CARBON COMPOUNDS
CARBON OXIDES
CARBOXYLIC ACIDS
CHALCOGENIDES
CHEMICAL REACTIONS
DECOMPOSITION
ELEMENTS
ENERGY
GLOBIN
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
MAMMALS
METALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PIGMENTS
PORPHYRINS
PRIMATES
PROTEINS
TRANSITION ELEMENTS
VERTEBRATES
550200* - Biochemistry
400500 - Photochemistry