1kkb: Difference between revisions
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New page: left|200px<br /><applet load="1kkb" size="450" color="white" frame="true" align="right" spinBox="true" caption="1kkb, resolution 2.6Å" /> '''Complex of Escherichi... |
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[[Image:1kkb.gif|left|200px]]<br /><applet load="1kkb" size=" | [[Image:1kkb.gif|left|200px]]<br /><applet load="1kkb" size="350" color="white" frame="true" align="right" spinBox="true" | ||
caption="1kkb, resolution 2.6Å" /> | caption="1kkb, resolution 2.6Å" /> | ||
'''Complex of Escherichia coli Adenylosuccinate Synthetase with IMP and Hadacidin'''<br /> | '''Complex of Escherichia coli Adenylosuccinate Synthetase with IMP and Hadacidin'''<br /> | ||
==Overview== | ==Overview== | ||
A complete set of substrate/substrate analogs of adenylosuccinate | A complete set of substrate/substrate analogs of adenylosuccinate synthetase from Escherichia coli induces dimer formation and a transition from a disordered to an ordered active site. The most striking of the ligand-induced effects is the movement of loop 40-53 by up to 9 A. Crystal structures of the partially ligated synthetase, which either combine IMP and hadacidin or IMP, hadacidin, and Mg(2+)-pyrophosphate, have ordered active sites, comparable with the fully ligated enzyme. More significantly, a crystal structure of the synthetase with IMP alone exhibits a largely ordered active site, which includes the 9 A movement of loop 40-53 but does not include conformational adjustments to backbone carbonyl 40 (Mg(2+) interaction element) and loop 298-304 (L-aspartate binding element). Interactions involving the 5'-phosphoryl group of IMP evidently trigger the formation of salt links some 30 A away. The above provides a structural basis for ligand binding synergism, effects on k(cat) due to mutations far from the site of catalysis, and the complete loss of substrate efficacy due to minor alterations of the 5'-phosphoryl group of IMP. | ||
==About this Structure== | ==About this Structure== | ||
1KKB 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 HAD and IMP 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:// | 1KKB 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=HAD:'>HAD</scene> and <scene name='pdbligand=IMP:'>IMP</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=1KKB OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: Escherichia coli]] | [[Category: Escherichia coli]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Fromm, H | [[Category: Fromm, H J.]] | ||
[[Category: Honzatko, R | [[Category: Honzatko, R B.]] | ||
[[Category: Hou, Z.]] | [[Category: Hou, Z.]] | ||
[[Category: Wang, W.]] | [[Category: Wang, W.]] | ||
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[[Category: purine nucleotide]] | [[Category: purine nucleotide]] | ||
''Page seeded by [http:// | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:35:05 2008'' | ||
