View source for 3uni


==Crystal Structure of Bovine Milk Xanthine Dehydrogenase with NADH Bound==
<StructureSection load='3uni' size='340' side='right'caption='[[3uni]], [[Resolution|resolution]] 2.20&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[3uni]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Bos_taurus Bos taurus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3UNI OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=3UNI FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.2&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CA:CALCIUM+ION'>CA</scene>, <scene name='pdbligand=CO3:CARBONATE+ION'>CO3</scene>, <scene name='pdbligand=FAD:FLAVIN-ADENINE+DINUCLEOTIDE'>FAD</scene>, <scene name='pdbligand=FES:FE2/S2+(INORGANIC)+CLUSTER'>FES</scene>, <scene name='pdbligand=GOL:GLYCEROL'>GOL</scene>, <scene name='pdbligand=MOS:DIOXOTHIOMOLYBDENUM(VI)+ION'>MOS</scene>, <scene name='pdbligand=MTE:PHOSPHONIC+ACIDMONO-(2-AMINO-5,6-DIMERCAPTO-4-OXO-3,7,8A,9,10,10A-HEXAHYDRO-4H-8-OXA-1,3,9,10-TETRAAZA-ANTHRACEN-7-YLMETHYL)ESTER'>MTE</scene>, <scene name='pdbligand=NAI:1,4-DIHYDRONICOTINAMIDE+ADENINE+DINUCLEOTIDE'>NAI</scene>, <scene name='pdbligand=SAL:2-HYDROXYBENZOIC+ACID'>SAL</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=3uni FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3uni OCA], [https://pdbe.org/3uni PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=3uni RCSB], [https://www.ebi.ac.uk/pdbsum/3uni PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=3uni ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/XDH_BOVIN XDH_BOVIN] Key enzyme in purine degradation. Catalyzes the oxidation of hypoxanthine to xanthine. Catalyzes the oxidation of xanthine to uric acid. Contributes to the generation of reactive oxygen species.
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
In mammals, xanthine oxidoreductase can exist as xanthine dehydrogenase (XDH) and xanthine oxidase (XO). The two enzymes possess common redox active cofactors, which form an electron transfer (ET) pathway terminated by a flavin cofactor. In spite of identical protein primary structures, the redox potential difference between XDH and XO for the flavin semiquinone/hydroquinone pair (E(sq/hq)) is ~170 mV, a striking difference. The former greatly prefers NAD(+) as ultimate substrate for ET from the iron-sulfur cluster FeS-II via flavin while the latter only accepts dioxygen. In XDH (without NAD(+)), however, the redox potential of the electron donor FeS-II is 180 mV higher than that for the acceptor flavin, yielding an energetically uphill ET. On the basis of new 1.65, 2.3, 1.9, and 2.2 A resolution crystal structures for XDH, XO, the NAD(+)- and NADH-complexed XDH, E(sq/hq) were calculated to better understand how the enzyme activates an ET from FeS-II to flavin. The majority of the E(sq/hq) difference between XDH and XO originates from a conformational change in the loop at positions 423-433 near the flavin binding site, causing the differences in stability of the semiquinone state. There was no large conformational change observed in response to NAD(+) binding at XDH. Instead, the positive charge of the NAD(+) ring, deprotonation of Asp429, and capping of the bulk surface of the flavin by the NAD(+) molecule all contribute to altering E(sq/hq) upon NAD(+) binding to XDH.

Protein conformational gating of enzymatic activity in xanthine oxidoreductase.,Ishikita H, Eger BT, Okamoto K, Nishino T, Pai EF J Am Chem Soc. 2012 Jan 18;134(2):999-1009. Epub 2011 Dec 29. PMID:22145797<ref>PMID:22145797</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 3uni" style="background-color:#fffaf0;"></div>

==See Also==
*[[Xanthine dehydrogenase 3D structures|Xanthine dehydrogenase 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Bos taurus]]
[[Category: Large Structures]]
[[Category: Eger BT]]
[[Category: Nishino T]]
[[Category: Okamoto K]]
[[Category: Pai EF]]