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1ay0

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Revision as of 11:07, 22 November 2017

IDENTIFICATION OF CATALYTICALLY IMPORTANT RESIDUES IN YEAST TRANSKETOLASE

Structural highlights

1ay0 is a 2 chain structure with sequence from Atcc 18824. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Ligands:	,
Gene:	TKL1 (ATCC 18824)
Activity:	Transketolase, with EC number 2.2.1.1
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

[TKT1_YEAST] Catalyzes the transfer of a two-carbon ketol group from a ketose donor to an aldose acceptor, via a covalent intermediate with the cofactor thiamine pyrophosphate.^[1]

Evolutionary Conservation

Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.

Publication Abstract from PubMed

The possible roles of four histidine residues in the active site of yeast transketolase were examined by site-directed mutagenesis. Replacement of the invariant His69 with alanine yielded a mutant enzyme with 1.5% of the specific activity of the wild-type enzyme and with an increased KM for the donor. This residue is located at the bottom of the substrate cleft close to the C1 hydroxyl group of the donor substrate, and the side chain of His69 might be required for recognition of this hydroxyl group and possibly for maintenance of the proper orientation of the reaction intermediate, (alpha, beta-dihydroxyethyl)thiamin diphosphate. Amino acid replacements of His481 by alanine, serine, and glutamine resulted in mutant enzymes with significantly increased KM values for the donor substrate and specific activities of 4.4%, 1.9%, and 5.5% of the wild-type enzyme. The kinetic data suggest that this residue, although close to the C2 carbonyl oxygen of the substrate, is not absolutely required for stabilization of the negative charge that develops at this oxygen in the transition state. This points toward the 4'-NH2 group of the pyrimidine ring of thiamin diphosphate as the major source of charge stabilization. Mutations at positions His30 and His263 result in mutant enzymes severely impaired in catalytic activity (1.5% and less of the activity of wild-type transketolase). The KM value for the donor substrate was increased for the His30Ala mutant but remained unchanged in the His263Ala enzyme. The side chains of both residues interact with the C3 hydroxyl group of the donor substrate, and the results indicate that the two residues act in concert during proton abstraction of the C3 hydroxyl proton during catalysis.

Identification of catalytically important residues in yeast transketolase.,Wikner C, Nilsson U, Meshalkina L, Udekwu C, Lindqvist Y, Schneider G Biochemistry. 1997 Dec 16;36(50):15643-9. PMID:9398292^[2]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Wikner C, Meshalkina L, Nilsson U, Backstrom S, Lindqvist Y, Schneider G. His103 in yeast transketolase is required for substrate recognition and catalysis. Eur J Biochem. 1995 Nov 1;233(3):750-5. PMID:8521838
↑ Wikner C, Nilsson U, Meshalkina L, Udekwu C, Lindqvist Y, Schneider G. Identification of catalytically important residues in yeast transketolase. Biochemistry. 1997 Dec 16;36(50):15643-9. PMID:9398292 doi:10.1021/bi971606b

1 Structural highlights
2 Function
3 Evolutionary Conservation
4 Publication Abstract from PubMed
5 References

Proteopedia Page Contributors and Editors (what is this?)

OCA

Retrieved from "http://52.214.119.220/wiki/index.php/1ay0"

@@ Line 1: / Line 1: @@
 ==IDENTIFICATION OF CATALYTICALLY IMPORTANT RESIDUES IN YEAST TRANSKETOLASE==
 <StructureSection load='1ay0' size='340' side='right' caption='[[1ay0]], [[Resolution|resolution]] 2.60&Aring;' scene=''>
@@ Line 6: / Line 7: @@
 <tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">TKL1 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=4932 ATCC 18824])</td></tr>
 <tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/Transketolase Transketolase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.2.1.1 2.2.1.1] </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=1ay0 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1ay0 OCA], [http://pdbe.org/1ay0 PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=1ay0 RCSB], [http://www.ebi.ac.uk/pdbsum/1ay0 PDBsum]</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=1ay0 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1ay0 OCA], [http://pdbe.org/1ay0 PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=1ay0 RCSB], [http://www.ebi.ac.uk/pdbsum/1ay0 PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=1ay0 ProSAT]</span></td></tr>
 </table>
 == Function ==
@@ Line 29: / Line 30: @@
 </div>
 <div class="pdbe-citations 1ay0" style="background-color:#fffaf0;"></div>
-==See Also==
-*[[Transketolase|Transketolase]]
 == References ==
 <references/>

1ay0

From Proteopedia

Revision as of 11:07, 22 November 2017

IDENTIFICATION OF CATALYTICALLY IMPORTANT RESIDUES IN YEAST TRANSKETOLASE

Structural highlights

Function

Evolutionary Conservation

Publication Abstract from PubMed

References

Contents

Proteopedia Page Contributors and Editors (what is this?)

Views

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