4csc: Difference between revisions
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[[Image:4csc.gif|left|200px]] | [[Image:4csc.gif|left|200px]] | ||
'''STRUCTURE OF TERNARY COMPLEXES OF CITRATE SYNTHASE WITH D-AND L-MALATE: MECHANISTIC IMPLICATIONS''' | {{Structure | ||
|PDB= 4csc |SIZE=350|CAPTION= <scene name='initialview01'>4csc</scene>, resolution 1.9Å | |||
|SITE= | |||
|LIGAND= <scene name='pdbligand=MAL:MALTOSE'>MAL</scene> and <scene name='pdbligand=ACO:ACETYL COENZYME *A'>ACO</scene> | |||
|ACTIVITY= [http://en.wikipedia.org/wiki/Citrate_(Si)-synthase Citrate (Si)-synthase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.3.3.1 2.3.3.1] | |||
|GENE= | |||
}} | |||
'''STRUCTURE OF TERNARY COMPLEXES OF CITRATE SYNTHASE WITH D-AND L-MALATE: MECHANISTIC IMPLICATIONS''' | |||
==Overview== | ==Overview== | ||
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==About this Structure== | ==About this Structure== | ||
4CSC is a [ | 4CSC is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Gallus_gallus Gallus gallus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4CSC OCA]. | ||
==Reference== | ==Reference== | ||
1.9-A structures of ternary complexes of citrate synthase with D- and L-malate: mechanistic implications., Karpusas M, Holland D, Remington SJ, Biochemistry. 1991 Jun 18;30(24):6024-31. PMID:[http:// | 1.9-A structures of ternary complexes of citrate synthase with D- and L-malate: mechanistic implications., Karpusas M, Holland D, Remington SJ, Biochemistry. 1991 Jun 18;30(24):6024-31. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/2043640 2043640] | ||
[[Category: Citrate (Si)-synthase]] | [[Category: Citrate (Si)-synthase]] | ||
[[Category: Gallus gallus]] | [[Category: Gallus gallus]] | ||
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[[Category: oxo-acid-lyase]] | [[Category: oxo-acid-lyase]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Mar 20 19:09:19 2008'' | ||
Revision as of 20:09, 20 March 2008
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| , resolution 1.9Å | |||||||
|---|---|---|---|---|---|---|---|
| Ligands: | and | ||||||
| Activity: | Citrate (Si)-synthase, with EC number 2.3.3.1 | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
STRUCTURE OF TERNARY COMPLEXES OF CITRATE SYNTHASE WITH D-AND L-MALATE: MECHANISTIC IMPLICATIONS
OverviewOverview
The structures of four isomorphous crystals of ternary complexes of chicken heart citrate synthase with D- or L-malate and acetyl coenzyme A or carboxymethyl coenzyme A have been determined by X-ray crystallography and fully refined at 1.9-A resolution. The structures show that both L-malate and D-malate bind in a very similar way in the presence of acetylCoA and that the enzyme conformation is "closed". Hydrogen bond geometry is suggested to account for the difference in binding constants of the two stereoisomers. The structures suggest that steric hindrance can account for the observation that proton exchange of acetyl coenzyme A with solvent is catalyzed by citrate synthase in the presence of L-malate but not D-malate. The ternary complexes with malate reveal the mode of binding of the substrate acetylCoA in the ground state. The carbonyl oxygen of the acetyl group is hydrogen bonded to a water molecule and to histidine 274, allowing unambiguous identification of the orientation of this group. The structures support the hypothesis that carboxymethyl coenzyme A is a transition-state analogue for the enolization step of the reaction (Bayer et al., 1981) and additionally support proposed mechanisms for the condensation reaction (Karpusas et al., 1990; Alter et al., 1990).
About this StructureAbout this Structure
4CSC is a Single protein structure of sequence from Gallus gallus. Full crystallographic information is available from OCA.
ReferenceReference
1.9-A structures of ternary complexes of citrate synthase with D- and L-malate: mechanistic implications., Karpusas M, Holland D, Remington SJ, Biochemistry. 1991 Jun 18;30(24):6024-31. PMID:2043640
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