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Search The CSA
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Catalytic Site Atlas

CSA LITERATURE entry for 1fui

E.C. nameL-fucose isomerase
SpeciesEscherichia coli (Bacteria)
E.C. Number (IntEnz) 5.3.1.25
CSA Homologues of 1fui2ajt,2hxg,
CSA Entries With UniProtID P69922
CSA Entries With EC Number 5.3.1.25
PDBe Entry 1fui
PDBSum Entry 1fui
MACiE Entry M0095

Literature Report

IntroductionL-fuctose isomerase, also known as arabinose isomerase uses both L-fucose and arabinose as substrates, converting the aldo-hexoses to ketoses to prepare them for aldol cleavage within the L-fucose metabolism pathway.
MechansimSeveral mechanisms have been suggested for the aldose-ketose conversion, although crystallographic data has identified the general acid and base residues that would support an ene-diol mechanism.
Asp361 is thought to act as a general base towards the C1-OH of the cyclic substrate, initiating ring opening. Glu337 then abstracts the alpha proton to the aldehyde group, with concomitant deprotonation of Asp361 by the developing anion, forming an enol intermediate. Asp361 is now charged and acts as a base again but this time at the C2 enol OH, leading to the formation of a ketone group with simultaneous reprotonation of the C1 from Glu337, forming an alpha hydroxyl group. The product cyclises and leaves the active site while a hydroxyl coordinated to the catalytically essential Mn divalent cation deprotonates Asp361, regenerating the active site.
Reaction

Catalytic Sites for 1fui

Annotated By Reference To The Literature - Site 1 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
AspA361361macie:sideChainThe residue acts as a general base and acid towards the substrate, initiating ring opening and facilitating the aldose-ketose interconversion
GluA337337macie:sideChainThe residue acts as a general base and acid towards the substrate, facilitating the aldose-ketose interconversion.

Literature References

Notes:
Seemann JE
Structure and mechanism of L-fucose isomerase from Escherichia coli.
J Mol Biol 1997 273 256-268
PubMed: 9367760
Collyer CA
Observations of reaction intermediates and the mechanism of aldose-ketose interconversion by D-xylose isomerase.
Proc Natl Acad Sci U S A 1990 87 1362-1366
PubMed: 2304904
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