1d4f

<StructureSection load='1d4f' size='340' side='right' caption='[[1d4f]], [[Resolution|resolution]] 2.80&Aring;' scene=''>

<table><tr><td colspan='2'>[[1d4f]] is a 4 chain structure with sequence from [http://en.wikipedia.org/wiki/Buffalo_rat Buffalo rat]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1D4F OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1D4F FirstGlance]. <br>

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=ADN:ADENOSINE'>ADN</scene>, <scene name='pdbligand=NAD:NICOTINAMIDE-ADENINE-DINUCLEOTIDE'>NAD</scene></td></tr>

<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[1b3r|1b3r]]</td></tr>

<tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/Adenosylhomocysteinase Adenosylhomocysteinase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.3.1.1 3.3.1.1] </span></td></tr>

<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1d4f FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1d4f OCA], [http://pdbe.org/1d4f PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=1d4f RCSB], [http://www.ebi.ac.uk/pdbsum/1d4f PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=1d4f ProSAT]</span></td></tr>

[[http://www.uniprot.org/uniprot/SAHH_RAT SAHH_RAT]] Adenosylhomocysteine is a competitive inhibitor of S-adenosyl-L-methionine-dependent methyl transferase reactions; therefore adenosylhomocysteinase may play a key role in the control of methylations via regulation of the intracellular concentration of adenosylhomocysteine.

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== Publication Abstract from PubMed ==

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.

Effects of site-directed mutagenesis on structure and function of recombinant rat liver S-adenosylhomocysteine hydrolase. Crystal structure of D244E mutant enzyme.,Komoto J, Huang Y, Gomi T, Ogawa H, Takata Y, Fujioka M, Takusagawa F J Biol Chem. 2000 Oct 13;275(41):32147-56. PMID:10913437<ref>PMID:10913437</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

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<div class="pdbe-citations 1d4f" style="background-color:#fffaf0;"></div>

== References ==

<references/>

[[Category: Adenosylhomocysteinase]]

[[Category: Buffalo rat]]

[[Category: Fujioka, M]]

[[Category: Gomi, T]]

[[Category: Huang, Y]]

[[Category: Komoto, J]]

[[Category: Ogawa, H]]

[[Category: Takata, Y]]

[[Category: Takusagawa, F]]

[[Category: X-ray crystal structure]]