1r2n
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(New page: 200px<br /><applet load="1r2n" size="450" color="white" frame="true" align="right" spinBox="true" caption="1r2n" /> '''NMR structure of the all-trans retinal in da...)
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Revision as of 23:06, 20 November 2007
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NMR structure of the all-trans retinal in dark-adapted Bacteriorhodopsin
Overview
The two forms of bacteriorhodopsin present in the dark-adapted state, containing either all-trans or 13-cis,15-syn retinal, were examined by, using solution state NMR, and their structures were determined. Comparison, of the all-trans and the 13-cis,15-syn forms shows a shift in position of, about 0.25 A within the pocket of the protein. Comparing this to the, 13-cis,15-anti chromophore of the catalytic cycle M-intermediate, structure, the 13-cis,15-syn form demonstrates a less pronounced up-tilt, of the retinal C12[bond]C14 region, while leaving W182 and T178, essentially unchanged. The N[bond]H dipole of the Schiff base orients, toward the extracellular side in both forms, however, it reorients toward, the intracellular side in the 13-cis,15-anti configuration to form the, catalytic M-intermediate. Thus, the change of the N[bond]H dipole is, considered primarily responsible for energy storage, conformation changes, of the protein, and the deprotonation of the Schiff base. The structural, similarity of the all-trans and 13-cis,15-syn forms is taken as strong, evidence for the ion dipole dragging model by which proton (hydroxide ion), translocation follows the change of the dipole.
About this Structure
1R2N is a Single protein structure of sequence from Halobacterium salinarum with RET as ligand. Full crystallographic information is available from OCA.
Reference
The structures of the active center in dark-adapted bacteriorhodopsin by solution-state NMR spectroscopy., Patzelt H, Simon B, terLaak A, Kessler B, Kuhne R, Schmieder P, Oesterhelt D, Oschkinat H, Proc Natl Acad Sci U S A. 2002 Jul 23;99(15):9765-70. Epub 2002 Jul 15. PMID:12119389
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