4cts
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(New page: 200px<br /><applet load="4cts" size="450" color="white" frame="true" align="right" spinBox="true" caption="4cts, resolution 2.9Å" /> '''CRYSTAL STRUCTURE ANA...)
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Revision as of 17:24, 20 November 2007
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CRYSTAL STRUCTURE ANALYSIS AND MOLECULAR MODEL OF A COMPLEX OF CITRATE SYNTHASE WITH OXALOACETATE AND S-ACETONYL-COENZYME A
Overview
The crystal structure of the complex of pig heart citrate synthase and, oxaloacetate in the presence of the potent inhibitor S-acetonyl coenzyme A, has been determined at a nominal resolution of 2.9 A by Patterson search, techniques and refined by restrained crystallographic refinement. The, complex crystallizes in the presence of polyvinylpyrrolidone in space, group P4(3)2(1)2 with a = 101.5 A and c = 224.6 A, with one dimeric, molecule of molecular weight 100,000 in the asymmetric unit. The, crystallographic R factor is 0.194 for the 14,332 unique reflections, between 6.0 and 2.9 A resolution. The structures of two forms of citrate, synthase in the presence and absence of product molecules have been, determined recently and shown to differ in the relative arrangement of the, large and small domains ("closed" and "open" forms). The third crystal, form described here is also closed, but there is substantial rearrangement, within the small domain relative to either of the other crystal forms. We, conclude that this is a third structural state of the enzyme, and, catalytic activity of the enzyme depends on structural changes during the, course of the reaction affecting domain conformation also. The three, structures are compared, and it is shown that the large domain is, considerably more rigid than the small domain. The conformation of the, small domain adapts to the ligand. The inhibitor, and the, "coenzyme-A-binding segment" of the enzyme are disordered. No electron, density is observed for the inhibitor, and only weak density for the, coenzyme-A-binding segment. Electron density for oxaloacetate is well, defined. It binds in a very similar manner to citrate.
About this Structure
4CTS is a Single protein structure of sequence from Sus scrofa with OAA as ligand. Active as Citrate (Si)-synthase, with EC number 2.3.3.1 Full crystallographic information is available from OCA.
Reference
Crystal structure analysis and molecular model of a complex of citrate synthase with oxaloacetate and S-acetonyl-coenzyme A., Wiegand G, Remington S, Deisenhofer J, Huber R, J Mol Biol. 1984 Mar 25;174(1):205-19. PMID:6716477
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