1ju9
From Proteopedia
(New page: 200px<br /><applet load="1ju9" size="450" color="white" frame="true" align="right" spinBox="true" caption="1ju9, resolution 2.00Å" /> '''HORSE LIVER ALCOHOL ...) |
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| - | [[Image:1ju9.jpg|left|200px]]<br /><applet load="1ju9" size=" | + | [[Image:1ju9.jpg|left|200px]]<br /><applet load="1ju9" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1ju9, resolution 2.00Å" /> | caption="1ju9, resolution 2.00Å" /> | ||
'''HORSE LIVER ALCOHOL DEHYDROGENASE VAL292SER MUTANT'''<br /> | '''HORSE LIVER ALCOHOL DEHYDROGENASE VAL292SER MUTANT'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The participation of Val-292 in catalysis by alcohol dehydrogenase and the | + | The participation of Val-292 in catalysis by alcohol dehydrogenase and the involvement of dynamics were investigated. Val-292 interacts with the nicotinamide ring of the bound coenzyme and may facilitate hydride transfer. The substitution of Val-292 with Ser (V292S) increases the dissociation constants for the coenzymes (NAD(+) by 50-fold, NADH by 75-fold) and the turnover numbers by 3-7-fold. The V292S enzyme crystallized in the presence of NAD(+) and 2,3,4,5,6-pentafluorobenzyl alcohol has an open conformation similar to the structure of the wild-type apo-enzyme, rather than the closed conformation observed for ternary complexes with wild-type enzyme. The V292S substitution perturbs the conformational equilibrium of the enzyme and decreases the kinetic complexity, which permits study of the hydride transfer step with steady-state kinetics. Eyring plots show that the DeltaH for the oxidation (V(1)) of the protio and deuterio benzyl alcohols is 13 kcal/mol and that the kinetic isotope effect of 4.1 is essentially temperature-independent. Eyring plots for the catalytic efficiency for reduction of benzaldehyde (V(2)/K(p)) with NADH or NADD are distinctly convex, being temperature-dependent from 5 to 25 degrees C and temperature-independent from 25 to 50 degrees C; the kinetic isotope effect of 3.2 for V(2)/K(p) is essentially independent of the temperature. The temperature dependencies and isotope effects for V(1) and V(2)/K(p) are not adequately explained by semiclassical transition state theory and are better explained by hydride transfer occurring through vibrationally assisted tunneling. |
==About this Structure== | ==About this Structure== | ||
| - | 1JU9 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 and NAD 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:// | + | 1JU9 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> and <scene name='pdbligand=NAD:'>NAD</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=1JU9 OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Equus caballus]] | [[Category: Equus caballus]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Plapp, B | + | [[Category: Plapp, B V.]] |
[[Category: Ramaswamy, S.]] | [[Category: Ramaswamy, S.]] | ||
| - | [[Category: Rubach, J | + | [[Category: Rubach, J K.]] |
[[Category: NAD]] | [[Category: NAD]] | ||
[[Category: ZN]] | [[Category: ZN]] | ||
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[[Category: oxidoreductase]] | [[Category: oxidoreductase]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:26:48 2008'' |
Revision as of 11:26, 21 February 2008
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HORSE LIVER ALCOHOL DEHYDROGENASE VAL292SER MUTANT
Overview
The participation of Val-292 in catalysis by alcohol dehydrogenase and the involvement of dynamics were investigated. Val-292 interacts with the nicotinamide ring of the bound coenzyme and may facilitate hydride transfer. The substitution of Val-292 with Ser (V292S) increases the dissociation constants for the coenzymes (NAD(+) by 50-fold, NADH by 75-fold) and the turnover numbers by 3-7-fold. The V292S enzyme crystallized in the presence of NAD(+) and 2,3,4,5,6-pentafluorobenzyl alcohol has an open conformation similar to the structure of the wild-type apo-enzyme, rather than the closed conformation observed for ternary complexes with wild-type enzyme. The V292S substitution perturbs the conformational equilibrium of the enzyme and decreases the kinetic complexity, which permits study of the hydride transfer step with steady-state kinetics. Eyring plots show that the DeltaH for the oxidation (V(1)) of the protio and deuterio benzyl alcohols is 13 kcal/mol and that the kinetic isotope effect of 4.1 is essentially temperature-independent. Eyring plots for the catalytic efficiency for reduction of benzaldehyde (V(2)/K(p)) with NADH or NADD are distinctly convex, being temperature-dependent from 5 to 25 degrees C and temperature-independent from 25 to 50 degrees C; the kinetic isotope effect of 3.2 for V(2)/K(p) is essentially independent of the temperature. The temperature dependencies and isotope effects for V(1) and V(2)/K(p) are not adequately explained by semiclassical transition state theory and are better explained by hydride transfer occurring through vibrationally assisted tunneling.
About this Structure
1JU9 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
Contributions of valine-292 in the nicotinamide binding site of liver alcohol dehydrogenase and dynamics to catalysis., Rubach JK, Ramaswamy S, Plapp BV, Biochemistry. 2001 Oct 23;40(42):12686-94. PMID:11601993
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