1axg
From Proteopedia
(New page: 200px<br /><applet load="1axg" size="450" color="white" frame="true" align="right" spinBox="true" caption="1axg, resolution 2.5Å" /> '''CRYSTAL STRUCTURE OF ...) |
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| - | [[Image:1axg.gif|left|200px]]<br /><applet load="1axg" size=" | + | [[Image:1axg.gif|left|200px]]<br /><applet load="1axg" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1axg, resolution 2.5Å" /> | caption="1axg, resolution 2.5Å" /> | ||
'''CRYSTAL STRUCTURE OF THE VAL203->ALA MUTANT OF LIVER ALCOHOL DEHYDROGENASE COMPLEXED WITH COFACTOR NAD AND INHIBITOR TRIFLUOROETHANOL SOLVED TO 2.5 ANGSTROM RESOLUTION'''<br /> | '''CRYSTAL STRUCTURE OF THE VAL203->ALA MUTANT OF LIVER ALCOHOL DEHYDROGENASE COMPLEXED WITH COFACTOR NAD AND INHIBITOR TRIFLUOROETHANOL SOLVED TO 2.5 ANGSTROM RESOLUTION'''<br /> | ||
==Overview== | ==Overview== | ||
| - | We present evidence that the size of an active site side chain may | + | We present evidence that the size of an active site side chain may modulate the degree of hydrogen tunneling in an enzyme-catalyzed reaction. Primary and secondary kH/kT and kD/kT kinetic isotope effects have been measured for the oxidation of benzyl alcohol catalyzed by horse liver alcohol dehydrogenase at 25 degrees C. As reported in earlier studies, the relationship between secondary kH/kT and kD/kT isotope effects provides a sensitive probe for deviations from classical behavior. In the present work, catalytic efficiency and the extent of hydrogen tunneling have been correlated for the alcohol dehydrogenase-catalyzed hydride transfer among a group of site-directed mutants at position 203. Val-203 interacts with the opposite face of the cofactor NAD+ from the alcohol substrate. The reduction in size of this residue is correlated with diminished tunneling and a two orders of magnitude decrease in catalytic efficiency. Comparison of the x-ray crystal structures of a ternary complex of a high-tunneling (Phe-93 --> Trp) and a low-tunneling (Val-203 --> Ala) mutant provides a structural basis for the observed effects, demonstrating an increase in the hydrogen transfer distance for the low-tunneling mutant. The Val-203 --> Ala ternary complex crystal structure also shows a hyperclosed interdomain geometry relative to the wild-type and the Phe-93 --> Trp mutant ternary complex structures. This demonstrates a flexibility in interdomain movement that could potentially narrow the distance between the donor and acceptor carbons in the native enzyme and may enhance the role of tunneling in the hydride transfer reaction. |
==About this Structure== | ==About this Structure== | ||
| - | 1AXG is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Equus_caballus Equus caballus] with ZN, NAD and ETF as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Alcohol_dehydrogenase Alcohol dehydrogenase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.1.1.1 1.1.1.1] Full crystallographic information is available from [http:// | + | 1AXG is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Equus_caballus Equus caballus] with <scene name='pdbligand=ZN:'>ZN</scene>, <scene name='pdbligand=NAD:'>NAD</scene> and <scene name='pdbligand=ETF:'>ETF</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Alcohol_dehydrogenase Alcohol dehydrogenase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.1.1.1 1.1.1.1] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1AXG OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Equus caballus]] | [[Category: Equus caballus]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Bahnson, B | + | [[Category: Bahnson, B J.]] |
| - | [[Category: Chin, J | + | [[Category: Chin, J K.]] |
| - | [[Category: Colby, T | + | [[Category: Colby, T D.]] |
| - | [[Category: Goldstein, B | + | [[Category: Goldstein, B M.]] |
| - | [[Category: Klinman, J | + | [[Category: Klinman, J P.]] |
[[Category: ETF]] | [[Category: ETF]] | ||
[[Category: NAD]] | [[Category: NAD]] | ||
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[[Category: oxidoreductase (nad(a)-choh(d))]] | [[Category: oxidoreductase (nad(a)-choh(d))]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 11:49:14 2008'' |
Revision as of 09:49, 21 February 2008
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CRYSTAL STRUCTURE OF THE VAL203->ALA MUTANT OF LIVER ALCOHOL DEHYDROGENASE COMPLEXED WITH COFACTOR NAD AND INHIBITOR TRIFLUOROETHANOL SOLVED TO 2.5 ANGSTROM RESOLUTION
Overview
We present evidence that the size of an active site side chain may modulate the degree of hydrogen tunneling in an enzyme-catalyzed reaction. Primary and secondary kH/kT and kD/kT kinetic isotope effects have been measured for the oxidation of benzyl alcohol catalyzed by horse liver alcohol dehydrogenase at 25 degrees C. As reported in earlier studies, the relationship between secondary kH/kT and kD/kT isotope effects provides a sensitive probe for deviations from classical behavior. In the present work, catalytic efficiency and the extent of hydrogen tunneling have been correlated for the alcohol dehydrogenase-catalyzed hydride transfer among a group of site-directed mutants at position 203. Val-203 interacts with the opposite face of the cofactor NAD+ from the alcohol substrate. The reduction in size of this residue is correlated with diminished tunneling and a two orders of magnitude decrease in catalytic efficiency. Comparison of the x-ray crystal structures of a ternary complex of a high-tunneling (Phe-93 --> Trp) and a low-tunneling (Val-203 --> Ala) mutant provides a structural basis for the observed effects, demonstrating an increase in the hydrogen transfer distance for the low-tunneling mutant. The Val-203 --> Ala ternary complex crystal structure also shows a hyperclosed interdomain geometry relative to the wild-type and the Phe-93 --> Trp mutant ternary complex structures. This demonstrates a flexibility in interdomain movement that could potentially narrow the distance between the donor and acceptor carbons in the native enzyme and may enhance the role of tunneling in the hydride transfer reaction.
About this Structure
1AXG is a Single protein structure of sequence from Equus caballus with , and as ligands. Active as Alcohol dehydrogenase, with EC number 1.1.1.1 Full crystallographic information is available from OCA.
Reference
A link between protein structure and enzyme catalyzed hydrogen tunneling., Bahnson BJ, Colby TD, Chin JK, Goldstein BM, Klinman JP, Proc Natl Acad Sci U S A. 1997 Nov 25;94(24):12797-802. PMID:9371755
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