Open AccessNonexponential protein relaxation: dynamics of conformational change in myoglobin.
Author(s) -
Manho Lim,
Tim Jackson,
Philip Anfinrud
Publication year - 1993
Publication title -
proceedings of the national academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.90.12.5801
Subject(s) - myoglobin , chemistry , picosecond , porphyrin , photodissociation , protein dynamics , relaxation (psychology) , conformational change , molecular dynamics , crystallography , photochemistry , dynamics (music) , chemical physics , computational chemistry , stereochemistry , physics , psychology , social psychology , laser , organic chemistry , acoustics , optics
The picosecond evolution of the tertiary conformation of myoglobin (Mb) after photodissociation of MbCO was investigated at room temperature by probing band III, a weak iron-porphyrin charge-transfer transition near 13,110 cm-1 (763 nm) that 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 dynamics for this functionally important motion are highly nonexponential, in agreement with recent molecular dynamics simulations [Kuczera, K., Lambry, J.-C., Martin, J.-L. & Karplus, M. (1993) Proc. Natl. Acad. Sci. USA 90, 5805-5807]. The conformational change likely affects the height of the barrier to ligand rebinding and may explain nonexponential NO rebinding.
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