1omd
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(New page: 200px<br /><applet load="1omd" size="450" color="white" frame="true" align="right" spinBox="true" caption="1omd, resolution 1.85Å" /> '''STRUCTURE OF ONCOMOD...)
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Revision as of 20:53, 20 November 2007
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STRUCTURE OF ONCOMODULIN REFINED AT 1.85 ANGSTROMS RESOLUTION. AN EXAMPLE OF EXTENSIVE MOLECULAR AGGREGATION VIA CA2+
Overview
The crystal structure of oncomodulin, a 12,000 Mr protein isolated from, rat tumours, has been determined by molecular replacement using the carp, parvalbumin structure as a starting model. Refinement was performed by, cycles of molecular fitting and restrained least-squares, using, area-detector intensity data to 1.85 A resolution. For the 5770, reflections in the range 6.0 to 1.85 A, which were used in the refinement, the crystallographic R-factor is 0.166. The refined model includes, residues 2 to 108, three Ca2+ and 87 water molecules per oncomodulin, molecule. The oncomodulin backbone is closely related to that of, parvalbumin; however, some differences are found after a least-squares fit, of the two backbones, with root-mean-square (r.m.s.) deviations of 1 to 2, A in residues 2 to 6, 59 to 61 of the CD loop, 87, 90 and 108. The overall, r.m.s. deviation of the backbone residues 5 to 108 is 0.62 A. Each of the, two Ca2+ atoms that are bound to the CD and EF loops is co-ordinated to, seven oxygen atoms, including one water molecule. The third Ca2+ is also, seven-co-ordinated, to five oxygen atoms belonging to three different, oncomodulin molecules and to two water molecules which form hydrogen bonds, to a fourth oncomodulin; thus, this intermolecular Ca2+ and its, equivalents interlink the molecules into zigzag layers normal to the b, axis with a spacing of b/2 or 32.14 A. No such extensive molecular, aggregation has been reported for any of the related Ca-binding regulatory, proteins of the troponin-C family studied thus far. The Ca-O distances in, all three polyhedra are in the range 2.07 A to 2.64 A, indicating tightly, bound Ca polyhedra.
About this Structure
1OMD is a Single protein structure of sequence from Rattus norvegicus with CA as ligand. Full crystallographic information is available from OCA.
Reference
Structure of oncomodulin refined at 1.85 A resolution. An example of extensive molecular aggregation via Ca2+., Ahmed FR, Przybylska M, Rose DR, Birnbaum GI, Pippy ME, MacManus JP, J Mol Biol. 1990 Nov 5;216(1):127-40. PMID:2231727
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