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| - | [[Image:1n8k.jpg|left|200px]] | + | {{Seed}} |
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| | {{STRUCTURE_1n8k| PDB=1n8k | SCENE= }} | | {{STRUCTURE_1n8k| PDB=1n8k | SCENE= }} |
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| - | '''Horse Liver Alcohol Dehydrogenase Val292Thr Mutant Complexed to NAD+ and Pyrazole'''
| + | ===Horse Liver Alcohol Dehydrogenase Val292Thr Mutant Complexed to NAD+ and Pyrazole=== |
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| - | ==Overview==
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| - | Amino acid residues Thr-178, Val-203, and Val-292, which interact with the nicotinamide ring of the coenzyme bound to alcohol dehydrogenase (ADH), may facilitate hydride transfer and hydrogen tunneling by orientation and dynamic effects. The T178S, T178V, V203A, V292A, V292S, and V292T substitutions significantly alter the steady state and transient kinetics of the enzyme. The V292A, V292S, and V292T enzymes have decreased affinity for coenzyme (NAD+ by 30-50-fold and NADH by 35-75-fold) as compared to the wild-type enzyme. The substitutions in the nicotinamide binding site decrease the rate constant of hydride transfer for benzyl alcohol oxidation by 3-fold (for V292T ADH) to 16-fold (for V203A ADH). The modest effects suggest that catalysis does not depend critically on individual residues and that several residues in the nicotinamide binding site contribute to catalysis. The structures of the V292T ADH-NAD+-pyrazole and wild-type ADH-NAD+-4-iodopyrazole ternary complexes are very similar. Only subtle changes in the V292T enzyme cause the large changes in coenzyme binding and the small change in hydride transfer. In these complexes, one pyrazole nitrogen binds to the catalytic zinc, and the other nitrogen forms a partial covalent bond with C4 of the nicotinamide ring, which adopts a boat conformation that is postulated to be relevant for hydride transfer. The results provide an experimental basis for evaluating the contributions of dynamics to hydride transfer.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_12627956}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 12627956 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_12627956}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Nicotinamide coenzyme]] | | [[Category: Nicotinamide coenzyme]] |
| | [[Category: Pyrazole]] | | [[Category: Pyrazole]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 02:13:38 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 20:31:14 2008'' |
Revision as of 17:31, 27 July 2008
Template:STRUCTURE 1n8k
Horse Liver Alcohol Dehydrogenase Val292Thr Mutant Complexed to NAD+ and Pyrazole
Template:ABSTRACT PUBMED 12627956
About this Structure
1N8K is a Single protein structure of sequence from Equus caballus. Full crystallographic information is available from OCA.
Reference
Amino acid residues in the nicotinamide binding site contribute to catalysis by horse liver alcohol dehydrogenase., Rubach JK, Plapp BV, Biochemistry. 2003 Mar 18;42(10):2907-15. PMID:12627956
Page seeded by OCA on Sun Jul 27 20:31:14 2008
