2bwh
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LAUE STRUCTURE OF A SHORT LIVED STATE OF L29W MYOGLOBIN
OverviewOverview
By using time-resolved x-ray crystallography at room temperature, structural relaxations and ligand migration were examined in myoglobin, (Mb) mutant L29W from nanoseconds to seconds after photodissociation of, carbon monoxide (CO) from the heme iron by nanosecond laser pulses. The, data were analyzed in terms of transient kinetics by fitting trial, functions to integrated difference electron density values obtained from, select structural moieties, thus allowing a quantitative description of, the processes involved. The observed relaxations are linked to other, investigations on protein dynamics. At the earliest times, the heme has, already completely relaxed into its domed deoxy structure, and there is no, photo-dissociated CO visible at the primary docking site. Initial, relaxations of larger globin moieties are completed within several hundred, nanoseconds. They influence the concomitant migration of photo-dissociated, CO to the Xe1 site, where it appears at approximately 300 ns and leaves, again at approximately 1.5 ms. The extremely long residence time in Xe1 as, compared with wild-type MbCO implies that, in the latter protein, the CO, exits the protein from Xe1 predominantly via the distal pocket. A, well-defined deligated state is populated between approximately 2 micros, and approximately 1 ms; its structure is very similar to the equilibrium, deoxy structure. Between 1.5 and 20 ms, no CO is visible in the protein, interior; it is either distributed among many sites within the protein or, has escaped to the solvent. Finally, recombination at the heme iron occurs, after >20 ms.
About this StructureAbout this Structure
2BWH is a Single protein structure of sequence from [1] with HEM and CMO as ligands. Known structural/functional Site: . Full crystallographic information is available from OCA.
ReferenceReference
Ligand migration pathway and protein dynamics in myoglobin: a time-resolved crystallographic study on L29W MbCO., Schmidt M, Nienhaus K, Pahl R, Krasselt A, Anderson S, Parak F, Nienhaus GU, Srajer V, Proc Natl Acad Sci U S A. 2005 Aug 16;102(33):11704-9. Epub 2005 Aug 5. PMID:16085709
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