1uno
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(New page: 200px<br /><applet load="1uno" size="450" color="white" frame="true" align="right" spinBox="true" caption="1uno, resolution 1.4Å" /> '''CRYSTAL STRUCTURE OF ...)
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Revision as of 02:07, 25 November 2007
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CRYSTAL STRUCTURE OF A D,L-ALTERNATING PEPTIDE
Overview
The crystal structure of H-(L-Tyr-D-Tyr)(4)-L-Lys-OH has been determined, to 1.3 A resolution. The D,L-alternating peptide crystallizes in the, tetragonal system, space group P4(3)2(1)2, with unit-cell parameters a = b, = 27.99 (3), c = 78.93 (8) A. The crystals contain two molecules in the, asymmetric unit that form a double-stranded right-handed antiparallel, beta-helix. The structure has been solved by SIRAS using a crystal soaked, in an iodide-containing solution for 1 min. The programs SHELXD and SHELXE, were used to determine the iodide substructure and also the experimental, electron-density map. Using the coordinates of known D,L-peptides, deposited in the PDB, several attempts were made to solve the structure by, molecular-replacement techniques. Although the backbone of the MR model, selected shows great similarity and was used to trace the actual peptide, structure in the map, it was not possible to obtain the correct solution, before the experimental phases became available. The correct fragment, orientations are easily determined, but the same does not apply to the, translation search. Nevertheless, insights into fragment search and, expansion were gained from the tests described in this paper. The, correlation coefficient calculated with the resolution shell of data, around 2.4 A, a distance corresponding to most 1-3 interatomic vectors, is, a particularly good discriminator of correct orientations in the rotation, search of small fragments.
About this Structure
1UNO is a Single protein structure of sequence from [1]. Full crystallographic information is available from OCA.
Reference
Solution and structure of an alternating D,L-peptide., Alexopoulos E, Kusel A, Sheldrick GM, Diederichsen U, Uson I, Acta Crystallogr D Biol Crystallogr. 2004 Nov;60(Pt 11):1971-80. Epub 2004, Oct 20. PMID:15502304
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