'''REFINEMENT OF THE SPATIAL STRUCTURE OF THE GRAMICIDIN A TRANSMEMBRANE ION-CHANNEL (RUSSIAN)'''
===REFINEMENT OF THE SPATIAL STRUCTURE OF THE GRAMICIDIN A TRANSMEMBRANE ION-CHANNEL (RUSSIAN)===
==Overview==
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The spatial structure of the gramicidin A (GA) transmembrane ion-channel was refined on the base of cross-peak volumes measured in NOESY spectra (mixing time tau m = 100 and 200 ms). The refinement methods included the comparison of experimental cross-peak volumes with those calculated for low-energy GA conformations, dynamic averaging of the low-energy conformation set and restrained energy minimization. Accuracy of the spatial structure determination was estimated by the penalty function Fr defined as a root mean square deviation of interproton distances corresponding to the calculated and experimental cross-peak volumes. As the initial conformation we used the right-handed pi 6,3 LD pi 6,3 LD helix established on the base of NMR data regardless of the cross-peak volumes. The conformation is in a good agreement with NOE cross-peak volumes (Fr 0.2 to 0.5 A depending on NOESY spectrum). For a number of NOEs formed by the side chain protons, distances errors were found as much as 0.5-2.0 A. Restrained energy minimization procedure had little further success. However some of these errors were eliminated by the change in torsional angle chi 2 of D-Leu12 and dynamic averaging of the Val7 side chain conformations. Apparently, majority of deviations of the calculated and experimental cross-peak volumes are due to the intramolecular mobility of GA and cannot be eliminated within the framework of rigid globule model. In summary the spatial structure of GA ion-channel can be thought as a set of low-energy conformations, differing by the side chain torsion angles chi 1 Val7 and chi 2 D-Leu4 and D-Leu10 and the orientation of the C-terminal ethanolamine group. Root mean square differences between the atomic coordinates of conformations are in the range of 0.3-0.8 A.
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{{ABSTRACT_PUBMED_1376600}}
==About this Structure==
==About this Structure==
Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1GRM OCA].
Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1GRM OCA].
==Reference==
==Reference==
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[[Category: Orekhov, V Y.]]
[[Category: Orekhov, V Y.]]
[[Category: Peptide antibiotic]]
[[Category: Peptide antibiotic]]
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Revision as of 05:57, 1 July 2008
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REFINEMENT OF THE SPATIAL STRUCTURE OF THE GRAMICIDIN A TRANSMEMBRANE ION-CHANNEL (RUSSIAN)REFINEMENT OF THE SPATIAL STRUCTURE OF THE GRAMICIDIN A TRANSMEMBRANE ION-CHANNEL (RUSSIAN)
Full experimental information is available from OCA.
ReferenceReference
[Refinement of the spatial structure of the gramicidin A ion channel], Lomize AL, Orekhov VIu, Arsen'ev AS, Bioorg Khim. 1992 Feb;18(2):182-200. PMID:1376600
