2gcq
From Proteopedia
(New page: 200px<br /><applet load="2gcq" size="450" color="white" frame="true" align="right" spinBox="true" caption="2gcq, resolution 2.0Å" /> '''Fully ligated E.Coli ...) |
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| - | [[Image:2gcq.jpg|left|200px]]<br /><applet load="2gcq" size=" | + | [[Image:2gcq.jpg|left|200px]]<br /><applet load="2gcq" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="2gcq, resolution 2.0Å" /> | caption="2gcq, resolution 2.0Å" /> | ||
'''Fully ligated E.Coli Adenylosuccinate Synthetase with GTP, 2'-deoxy-IMP and Hadacidin'''<br /> | '''Fully ligated E.Coli Adenylosuccinate Synthetase with GTP, 2'-deoxy-IMP and Hadacidin'''<br /> | ||
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==About this Structure== | ==About this Structure== | ||
| - | 2GCQ is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with MG, DOI, GDP and HAD as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Adenylosuccinate_synthase Adenylosuccinate synthase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=6.3.4.4 6.3.4.4] Full crystallographic information is available from [http:// | + | 2GCQ is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with <scene name='pdbligand=MG:'>MG</scene>, <scene name='pdbligand=DOI:'>DOI</scene>, <scene name='pdbligand=GDP:'>GDP</scene> and <scene name='pdbligand=HAD:'>HAD</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Adenylosuccinate_synthase Adenylosuccinate synthase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=6.3.4.4 6.3.4.4] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2GCQ OCA]. |
==Reference== | ==Reference== | ||
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[[Category: adenylosuccinate synthetase; adss; gtp; hadacidin; 2'-deoxy-imp]] | [[Category: adenylosuccinate synthetase; adss; gtp; hadacidin; 2'-deoxy-imp]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Jan 23 15:34:26 2008'' |
Revision as of 13:34, 23 January 2008
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Fully ligated E.Coli Adenylosuccinate Synthetase with GTP, 2'-deoxy-IMP and Hadacidin
Overview
Adenylosuccinate synthetase catalyzes the first committed step in the de, novo biosynthesis of AMP, coupling L-aspartate and IMP to form, adenylosuccinate. Km values of IMP and 2'-deoxy-IMP are nearly identical, with each substrate supporting comparable maximal velocities. Nonetheless, the Km value for L-aspartate and the Ki value for hadacidin (a competitive, inhibitor with respect to L-aspartate) are 29-57-fold lower in the, presence of IMP than in the presence of 2'-deoxy-IMP. Crystal structures, of the synthetase ligated with hadacidin, GDP, and either 6-phosphoryl-IMP, or 2'-deoxy-6-phosphoryl-IMP are identical except for the presence of a, cavity normally occupied by the 2'-hydroxyl group of IMP. In the presence, of 6-phosphoryl-IMP and GDP (hadacidin absent), the L-aspartate pocket can, retain its fully ligated conformation, forming hydrogen bonds between the, 2'-hydroxyl group of IMP and sequence-invariant residues. In the presence, of 2'-deoxy-6-phosphoryl-IMP and GDP, however, the L-aspartate pocket is, poorly ordered. The absence of the 2'-hydroxyl group of the, deoxyribonucleotide may destabilize binding of the ligand to the, L-aspartate pocket by disrupting hydrogen bonds that maintain a favorable, protein conformation and by the introduction of a cavity into the fully, ligated active site. At an approximate energy cost of 2.2 kcal/mol, the, unfavorable thermodynamics of cavity formation may be the major factor in, destabilizing ligands at the L-aspartate pocket.
About this Structure
2GCQ is a Single protein structure of sequence from Escherichia coli with , , and as ligands. Active as Adenylosuccinate synthase, with EC number 6.3.4.4 Full crystallographic information is available from OCA.
Reference
Cavitation as a mechanism of substrate discrimination by adenylosuccinate synthetases., Iancu CV, Zhou Y, Borza T, Fromm HJ, Honzatko RB, Biochemistry. 2006 Sep 26;45(38):11703-11. PMID:16981730
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