1csh
From Proteopedia
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|PDB= 1csh |SIZE=350|CAPTION= <scene name='initialview01'>1csh</scene>, resolution 1.65Å | |PDB= 1csh |SIZE=350|CAPTION= <scene name='initialview01'>1csh</scene>, resolution 1.65Å | ||
|SITE= | |SITE= | ||
| - | |LIGAND= <scene name='pdbligand= | + | |LIGAND= <scene name='pdbligand=AMX:AMIDOCARBOXYMETHYLDETHIA+COENZYME+*A'>AMX</scene>, <scene name='pdbligand=OAA:OXALOACETATE+ION'>OAA</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] | + | |ACTIVITY= <span class='plainlinks'>[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] </span> |
|GENE= | |GENE= | ||
| + | |DOMAIN= | ||
| + | |RELATEDENTRY= | ||
| + | |RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1csh FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1csh OCA], [http://www.ebi.ac.uk/pdbsum/1csh PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1csh RCSB]</span> | ||
}} | }} | ||
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[[Category: Remington, S J.]] | [[Category: Remington, S J.]] | ||
[[Category: Usher, K C.]] | [[Category: Usher, K C.]] | ||
| - | [[Category: AMX]] | ||
| - | [[Category: OAA]] | ||
[[Category: lyase(oxo-acid)]] | [[Category: lyase(oxo-acid)]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Mar 30 19:27:49 2008'' |
Revision as of 16:27, 30 March 2008
| |||||||
| , resolution 1.65Å | |||||||
|---|---|---|---|---|---|---|---|
| Ligands: | , | ||||||
| Activity: | Citrate (Si)-synthase, with EC number 2.3.3.1 | ||||||
| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
A VERY SHORT HYDROGEN BOND PROVIDES ONLY MODERATE STABILIZATION OF AN ENZYME: INHIBITOR COMPLEX OF CITRATE SYNTHASE
Overview
Two extremely potent inhibitors of citrate synthase, carboxyl and primary amide analogues of acetyl coenzyme A, have been synthesized. The ternary complexes of these inhibitors with oxaloacetate and citrate synthase have been crystallized and their structures analyzed at 1.70- and 1.65-A resolution, respectively. The inhibitors have dissociation constants in the nanomolar range, with the carboxyl analogue binding more tightly (Ki = 1.6 nM at pH 6.0) than the amide analogue (28 nM), despite the unfavorable requirement for proton uptake by the former. The carboxyl group forms a shorter hydrogen bond with the catalytic Asp 375 (distance < 2.4 A) than does the amide group (distance approximately 2.5 A). Particularly with the carboxylate inhibitor, the very short hydrogen bond distances measured suggest a low barrier or short strong hydrogen bond. However, the binding constants differ by only a factor of 20 at pH 6.0, corresponding to an increase in binding energy for the carboxyl analogue on the enzyme of about 2 kcal/mol more than the amide analogue, much less than has been proposed for short strong hydrogen bonds based on gas phase measurements [> 20 kcal/mol (Gerlt & Gassman, 1993a,b)]. The inhibitor complexes support proposals that Asp 375 and His 274 work in concert to form an enolized form of acetyl-coenzyme A as the first step in the reaction.
About this Structure
1CSH is a Single protein structure of sequence from Gallus gallus. Full crystallographic information is available from OCA.
Reference
A very short hydrogen bond provides only moderate stabilization of an enzyme-inhibitor complex of citrate synthase., Usher KC, Remington SJ, Martin DP, Drueckhammer DG, Biochemistry. 1994 Jun 28;33(25):7753-9. PMID:8011640
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