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1kt8

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[[Image:1kt8.jpg|left|200px]]<br /><applet load="1kt8" size="350" color="white" frame="true" align="right" spinBox="true"
 
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caption="1kt8, resolution 1.90&Aring;" />
 
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'''HUMAN BRANCHED CHAIN AMINO ACID AMINOTRANSFERASE (MITOCHONDRIAL): THREE DIMENSIONAL STRUCTURE OF ENZYME IN ITS KETIMINE FORM WITH THE SUBSTRATE L-ISOLEUCINE'''<br />
 
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==Overview==
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==HUMAN BRANCHED CHAIN AMINO ACID AMINOTRANSFERASE (MITOCHONDRIAL): THREE DIMENSIONAL STRUCTURE OF ENZYME IN ITS KETIMINE FORM WITH THE SUBSTRATE L-ISOLEUCINE==
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The three-dimensional structures of the isoleucine ketimine and the, pyridoxamine phosphate forms of human mitochondrial branched chain, aminotransferase (hBCATm) have been determined crystallographically at 1.9, A resolution. The hBCATm-catalyzed transamination can be described in, molecular terms together with the earlier solved pyridoxal phosphate forms, of the enzyme. The active site lysine, Lys202, undergoes large, conformational changes, and the pyridine ring of the cofactor tilts by, about 18 degrees during catalysis. A major determinant of the enzyme's, substrate and stereospecificity for L-branched chain amino acids is a, group of hydrophobic residues that form three hydrophobic surfaces and, lock the side chain in place. Short-chain aliphatic amino acid side chains, are unable to interact through van der Waals contacts with any of the, surfaces whereas bulky aromatic side chains would result in significant, steric hindrance. As shown by modeling, and in agreement with previous, biochemical data, glutamate but not aspartate can form hydrogen bond, interactions. The carboxylate group of the bound isoleucine is on the same, side as the phosphate group of the cofactor. These active site, interactions are largely retained in a model of the human cytosolic, branched chain aminotransferase (hBCATc), suggesting that residues in the, second tier of interactions are likely to determine the specificity of, hBCATc for the drug gabapentin. Finally, the structures reveal a unique, role for cysteine residues in the mammalian BCAT. Cys315 and Cys318, which, immediately follow a beta-turn (residues 311-314) and are located just, outside the active site, form an unusual thiol-thiolate hydrogen bond., This beta-turn positions Thr313 for its interaction with the pyridoxal, phosphate oxygens and substrate alpha-carboxylate group.
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<StructureSection load='1kt8' size='340' side='right'caption='[[1kt8]], [[Resolution|resolution]] 1.90&Aring;' scene=''>
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== Structural highlights ==
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<table><tr><td colspan='2'>[[1kt8]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1KT8 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1KT8 FirstGlance]. <br>
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</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.9&#8491;</td></tr>
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<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=ACY:ACETIC+ACID'>ACY</scene>, <scene name='pdbligand=GOL:GLYCEROL'>GOL</scene>, <scene name='pdbligand=ILP:N-[O-PHOSPHONO-PYRIDOXYL]-ISOLEUCINE'>ILP</scene></td></tr>
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<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1kt8 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1kt8 OCA], [https://pdbe.org/1kt8 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1kt8 RCSB], [https://www.ebi.ac.uk/pdbsum/1kt8 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1kt8 ProSAT]</span></td></tr>
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</table>
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== Function ==
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[https://www.uniprot.org/uniprot/BCAT2_HUMAN BCAT2_HUMAN] Catalyzes the first reaction in the catabolism of the essential branched chain amino acids leucine, isoleucine, and valine. May also function as a transporter of branched chain alpha-keto acids.
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== Evolutionary Conservation ==
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[[Image:Consurf_key_small.gif|200px|right]]
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Check<jmol>
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<jmolCheckbox>
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<scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/kt/1kt8_consurf.spt"</scriptWhenChecked>
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<scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
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<text>to colour the structure by Evolutionary Conservation</text>
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</jmolCheckbox>
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</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=1kt8 ConSurf].
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<div style="clear:both"></div>
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==Disease==
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==See Also==
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Known diseases associated with this structure: Hypervalinemia or hyperleucine-isoleucinemia (1) OMIM:[[http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=113530 113530]]
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*[[Aminotransferase 3D structures|Aminotransferase 3D structures]]
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__TOC__
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==About this Structure==
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</StructureSection>
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1KT8 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with <scene name='pdbligand=ILP:'>ILP</scene>, <scene name='pdbligand=ACY:'>ACY</scene> and <scene name='pdbligand=GOL:'>GOL</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Branched-chain-amino-acid_transaminase Branched-chain-amino-acid transaminase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.6.1.42 2.6.1.42] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1KT8 OCA].
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==Reference==
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Crystal structures of human mitochondrial branched chain aminotransferase reaction intermediates: ketimine and pyridoxamine phosphate forms., Yennawar NH, Conway ME, Yennawar HP, Farber GK, Hutson SM, Biochemistry. 2002 Oct 1;41(39):11592-601. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=12269802 12269802]
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[[Category: Branched-chain-amino-acid transaminase]]
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[[Category: Homo sapiens]]
[[Category: Homo sapiens]]
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[[Category: Single protein]]
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[[Category: Large Structures]]
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[[Category: Conway, M.E.]]
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[[Category: Conway ME]]
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[[Category: Farber, G.K.]]
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[[Category: Farber GK]]
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[[Category: Hutson, S.M.]]
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[[Category: Hutson SM]]
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[[Category: Yennawar, H.P.]]
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[[Category: Yennawar HP]]
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[[Category: Yennawar, N.H.]]
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[[Category: Yennawar NH]]
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[[Category: ACY]]
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[[Category: GOL]]
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[[Category: ILP]]
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[[Category: fold type iv]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri Feb 15 16:15:09 2008''
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Current revision

HUMAN BRANCHED CHAIN AMINO ACID AMINOTRANSFERASE (MITOCHONDRIAL): THREE DIMENSIONAL STRUCTURE OF ENZYME IN ITS KETIMINE FORM WITH THE SUBSTRATE L-ISOLEUCINE

PDB ID 1kt8

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