1cg4: Difference between revisions
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|PDB= 1cg4 |SIZE=350|CAPTION= <scene name='initialview01'>1cg4</scene>, resolution 2.5Å | |PDB= 1cg4 |SIZE=350|CAPTION= <scene name='initialview01'>1cg4</scene>, resolution 2.5Å | ||
|SITE= | |SITE= | ||
|LIGAND= <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene>, <scene name='pdbligand=IMO:6-O-PHOSPHORYL+INOSINE+MONOPHOSPHATE'>IMO</scene> and <scene name='pdbligand=GDP:GUANOSINE-5 | |LIGAND= <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene>, <scene name='pdbligand=IMO:6-O-PHOSPHORYL+INOSINE+MONOPHOSPHATE'>IMO</scene> and <scene name='pdbligand=GDP:GUANOSINE-5'-DIPHOSPHATE'>GDP</scene> | ||
|ACTIVITY= [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] | |ACTIVITY= [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] | ||
|GENE= | |GENE= | ||
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[[Category: purine 2 nucleotide biosynthesis]] | [[Category: purine 2 nucleotide biosynthesis]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Mar 23 11:22:30 2008'' | ||
Revision as of 12:22, 23 March 2008
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| , resolution 2.5Å | |||||||
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| Ligands: | , and | ||||||
| Activity: | Adenylosuccinate synthase, with EC number 6.3.4.4 | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
STRUCTURE OF THE MUTANT (R303L) OF ADENYLOSUCCINATE SYNTHETASE FROM E. COLI COMPLEXED WITH, GDP, 6-PHOSPHORYL-IMP, AND MG2+
OverviewOverview
Asp13 and His41 are essential residues of adenylosuccinate synthetase, putatively catalyzing the formation of adenylosuccinate from an intermediate of 6-phosphoryl-IMP. Wild-type adenylosuccinate synthetase and three mutant synthetases (Arg143 --> Leu, Lys16 --> Gln, and Arg303 --> Leu) from Eschericha coli have been crystallized in the presence of IMP, hadacidin (an analogue of L-aspartate), Mg2+, and GTP. The active site of each complex contains 6-phosphoryl-IMP, Mg2+, GDP, and hadacidin, except for the Arg303 --> Leu mutant, which does not bind hadacidin. In response to the formation of 6-phosphoryl-IMP, Asp13 enters the inner coordination sphere of the active site Mg2+. His41 hydrogen bonds with 6-phosphoryl-IMP, except in the Arg303 --> Leu complex, where it remains bound to the guanine nucleotide. Hence, recognition of the active site Mg2+ by Asp13 evidently occurs after the formation of 6-phosphoryl-IMP, but recognition of the intermediate by His41 may require the association of L-aspartate with the active site. Structures reported here support a mechanism in which Asp13 and His41 act as the catalytic base and acid, respectively, in the formation of 6-phosphoryl-IMP, and then act together as catalytic acids in the subsequent formation of adenylosuccinate.
About this StructureAbout this Structure
1CG4 is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
ReferenceReference
Mechanistic implications from crystalline complexes of wild-type and mutant adenylosuccinate synthetases from Escherichia coli., Choe JY, Poland BW, Fromm HJ, Honzatko RB, Biochemistry. 1999 May 25;38(21):6953-61. PMID:10346917
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