Dynamics of conformational relaxation in myoglobin

Manho Lim; Timothy A. Jackson; Philip A. Anfinrud

doi:10.1117/12.146122

17 June 1993 Dynamics of conformational relaxation in myoglobin

Manho Lim, Timothy A. Jackson, Philip A. Anfinrud

Proceedings Volume 1921, Laser Spectroscopy of Biomolecules; (1993) https://doi.org/10.1117/12.146122
Event: Laser Spectroscopy of Biomolecules: 4th International Conference on Laser Applications in Life Sciences, 1992, Jyvaskyla, Finland

Abstract

The picosecond evolution of the tertiary conformation of myoglobin following photodissociation of carbonmonoxymyoglobin was investigated at room temperature by probing band III, a weak iron-porphyrin charge-transfer transition near 13110 cm^-1 (763 nm) whose position is sensitive to the out-of-plane displacement of the iron. Upon photolysis, the iron moves out of the plane of the porphyrin causing a blue shift of band III and a concomitant change in the protein conformation. The conformational relaxation reveals a viscosity dependence even at early times (< 2 ps), indicating that the primary motion of the protein involves a displacement of the surrounding solvent. This motion likely corresponds to a displacement of the F-helix. The ensuing relaxation is highly nonexponential, in agreement with recent molecular dynamics simulations. The conformational changes occurring near the heme likely affect the height of the barrier to ligand rebinding and may explain nonexponential rebinding of ligands at ambient temperatures.

Citation Download Citation

Manho Lim, Timothy A. Jackson, and Philip A. Anfinrud "Dynamics of conformational relaxation in myoglobin", Proc. SPIE 1921, Laser Spectroscopy of Biomolecules, (17 June 1993); https://doi.org/10.1117/12.146122

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