Source:http://linkedlifedata.com/resource/pubmed/id/10913437
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| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
41
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| pubmed:dateCreated |
2000-11-13
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| pubmed:databankReference | |
| pubmed:abstractText |
A site-directed mutagenesis, D244E, of S-adenosylhomocysteine hydrolase (AdoHcyase) changes drastically the nature of the protein, especially the NAD(+) binding affinity. The mutant enzyme contained NADH rather than NAD(+) (Gomi, T., Takata, Y., Date, T., Fujioka, M., Aksamit, R. R., Backlund, P. S., and Cantoni, G. L. (1990) J. Biol. Chem. 265, 16102-16107). In contrast to the site-directed mutagenesis study, the crystal structures of human and rat AdoHcyase recently determined have shown that the carboxyl group of Asp-244 points in a direction opposite to the bound NAD molecule and does not participate in any hydrogen bonds with the NAD molecule. To explain the discrepancy between the mutagenesis study and the x-ray studies, we have determined the crystal structure of the recombinant rat-liver D244E mutant enzyme to 2.8-A resolution. The D244E mutation changes the enzyme structure from the open to the closed conformation by means of a approximately 17 degrees rotation of the individual catalytic domains around the molecular hinge sections. The D244E mutation shifts the catalytic reaction from a reversible to an irreversible fashion. The large affinity difference between NAD(+) and NADH is mainly due to the enzyme conformation, but not to the binding-site geometry; an NAD(+) in the open conformation is readily released from the enzyme, whereas an NADH in the closed conformation is trapped and cannot leave the enzyme. A catalytic mechanism of AdoHcyase has been proposed on the basis of the crystal structures of the wild-type and D244E enzymes.
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| pubmed:grant | |
| pubmed:language |
eng
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| pubmed:journal | |
| pubmed:citationSubset |
IM
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| pubmed:chemical | |
| pubmed:status |
MEDLINE
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| pubmed:month |
Oct
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| pubmed:issn |
0021-9258
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| pubmed:author | |
| pubmed:issnType |
Print
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| pubmed:day |
13
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| pubmed:volume |
275
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| pubmed:owner |
NLM
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| pubmed:authorsComplete |
Y
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| pubmed:pagination |
32147-56
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| pubmed:dateRevised |
2007-11-14
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| pubmed:meshHeading |
pubmed-meshheading:10913437-Adenosylhomocysteinase,
pubmed-meshheading:10913437-Amino Acid Substitution,
pubmed-meshheading:10913437-Animals,
pubmed-meshheading:10913437-Binding Sites,
pubmed-meshheading:10913437-Catalysis,
pubmed-meshheading:10913437-Catalytic Domain,
pubmed-meshheading:10913437-Crystallography, X-Ray,
pubmed-meshheading:10913437-Hydrogen Bonding,
pubmed-meshheading:10913437-Hydrolases,
pubmed-meshheading:10913437-Liver,
pubmed-meshheading:10913437-Models, Molecular,
pubmed-meshheading:10913437-Mutagenesis, Site-Directed,
pubmed-meshheading:10913437-Mutation,
pubmed-meshheading:10913437-NAD,
pubmed-meshheading:10913437-Protein Structure, Secondary,
pubmed-meshheading:10913437-Rats,
pubmed-meshheading:10913437-Recombinant Proteins,
pubmed-meshheading:10913437-Structure-Activity Relationship
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| pubmed:year |
2000
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| pubmed:articleTitle |
Effects of site-directed mutagenesis on structure and function of recombinant rat liver S-adenosylhomocysteine hydrolase. Crystal structure of D244E mutant enzyme.
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| pubmed:affiliation |
Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045-210, USA.
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| pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.
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