1ai3
From Proteopedia
(New page: 200px<br /><applet load="1ai3" size="450" color="white" frame="true" align="right" spinBox="true" caption="1ai3, resolution 1.9Å" /> '''ORBITAL STEERING IN T...) |
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| - | [[Image:1ai3.gif|left|200px]]<br /><applet load="1ai3" size=" | + | [[Image:1ai3.gif|left|200px]]<br /><applet load="1ai3" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1ai3, resolution 1.9Å" /> | caption="1ai3, resolution 1.9Å" /> | ||
'''ORBITAL STEERING IN THE CATALYTIC POWER OF ENZYMES: SMALL STRUCTURAL CHANGES WITH LARGE CATALYTIC CONSEQUENCES'''<br /> | '''ORBITAL STEERING IN THE CATALYTIC POWER OF ENZYMES: SMALL STRUCTURAL CHANGES WITH LARGE CATALYTIC CONSEQUENCES'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Small structural perturbations in the enzyme isocitrate dehydrogenase | + | Small structural perturbations in the enzyme isocitrate dehydrogenase (IDH) were made in order to evaluate the contribution of precise substrate alignment to the catalytic power of an enzyme. The reaction trajectory of IDH was modified (i) after the adenine moiety of nicotinamide adenine dinucleotide phosphate was changed to hypoxanthine (the 6-amino was changed to 6-hydroxyl), and (ii) by replacing Mg2+, which has six coordinating ligands, with Ca2+, which has eight coordinating ligands. Both changes make large (10(-3) to 10(-5)) changes in the reaction velocity but only small changes in the orientation of the substrates (both distance and angle) as revealed by cryocrystallographic trapping of active IDH complexes. The results provide evidence that orbital overlap produced by optimal orientation of reacting orbitals plays a major quantitative role in the catalytic power of enzymes. |
==About this Structure== | ==About this Structure== | ||
| - | 1AI3 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 NDO and ITM as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Isocitrate_dehydrogenase_(NADP(+)) Isocitrate dehydrogenase (NADP(+))], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.1.1.42 1.1.1.42] Full crystallographic information is available from [http:// | + | 1AI3 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=NDO:'>NDO</scene> and <scene name='pdbligand=ITM:'>ITM</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Isocitrate_dehydrogenase_(NADP(+)) Isocitrate dehydrogenase (NADP(+))], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.1.1.42 1.1.1.42] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1AI3 OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Isocitrate dehydrogenase (NADP(+))]] | [[Category: Isocitrate dehydrogenase (NADP(+))]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Junior, D | + | [[Category: Junior, D E.Koshland.]] |
[[Category: Mesecar, A.]] | [[Category: Mesecar, A.]] | ||
| - | [[Category: Stoddard, B | + | [[Category: Stoddard, B L.]] |
[[Category: ITM]] | [[Category: ITM]] | ||
[[Category: NDO]] | [[Category: NDO]] | ||
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[[Category: phosphorylation]] | [[Category: phosphorylation]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 11:44:43 2008'' |
Revision as of 09:44, 21 February 2008
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ORBITAL STEERING IN THE CATALYTIC POWER OF ENZYMES: SMALL STRUCTURAL CHANGES WITH LARGE CATALYTIC CONSEQUENCES
Overview
Small structural perturbations in the enzyme isocitrate dehydrogenase (IDH) were made in order to evaluate the contribution of precise substrate alignment to the catalytic power of an enzyme. The reaction trajectory of IDH was modified (i) after the adenine moiety of nicotinamide adenine dinucleotide phosphate was changed to hypoxanthine (the 6-amino was changed to 6-hydroxyl), and (ii) by replacing Mg2+, which has six coordinating ligands, with Ca2+, which has eight coordinating ligands. Both changes make large (10(-3) to 10(-5)) changes in the reaction velocity but only small changes in the orientation of the substrates (both distance and angle) as revealed by cryocrystallographic trapping of active IDH complexes. The results provide evidence that orbital overlap produced by optimal orientation of reacting orbitals plays a major quantitative role in the catalytic power of enzymes.
About this Structure
1AI3 is a Single protein structure of sequence from Escherichia coli with and as ligands. Active as Isocitrate dehydrogenase (NADP(+)), with EC number 1.1.1.42 Full crystallographic information is available from OCA.
Reference
Orbital steering in the catalytic power of enzymes: small structural changes with large catalytic consequences., Mesecar AD, Stoddard BL, Koshland DE Jr, Science. 1997 Jul 11;277(5323):202-6. PMID:9211842
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