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Search The CSA
PDB ID
UNIPROT ID
EC Number

Catalytic Site Atlas

CSA LITERATURE entry for 1lj1

E.C. namesuccinate dehydrogenase
SpeciesShewanella frigidimarina (Bacteria)
E.C. Number (IntEnz) 1.3.99.1
CSA Homologues of 1lj1
CSA Entries With UniProtID P0C278
CSA Entries With EC Number 1.3.99.1
PDBe Entry 1lj1
PDBSum Entry 1lj1
MACiE Entry M0020

Literature Report

IntroductionFumarate reductases are involved in bacterial anaerobic respiration with fumarate acting as a terminal electron acceptor. In Shewanella species, fumarate reductase is a soluble periplasmic, tetaheme, FAD-containing enzyme called flavocytochrome c3 (Fcc3).
MechansimOn binding at the active site, the C1 carboxylate group of the fumarate substrate is polarised and twisted out of the planar configuration by closure of the clamp domain and the resulting steric constraints.
The polar hydrogen bonding environment of the C4 carboxylate, as a result of interactions with His504, Arg544 and Arg402, polarises the C2-C3 bond of the substrate, causing C2 to become increasingly susceptible to nucleophilic attack and facilitating hydride transfer from N5 of the reduced flavin to the si face of the substrate. Concurrently, a proton is transferred to the substrate from His504.
In an oxidised environment, hydride transfer is not possible and a water molecule attacks on the re-face of the substrate instead.
Arg402 acts as an acid catalyst, transferring a proton to the substrate as part of a proton delivery pathway involving Arg381 and Glu378, resulting in the formation of the product, succinate.
Reaction

Catalytic Sites for 1lj1

Annotated By Reference To The Literature - Site 1 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
AlaA402402macie:sideChainError

Annotated By Reference To The Literature - Site 2 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
AlaB402402macie:sideChainArg402 transfers protons to the substrate as part of a proton delivery pathway involving Arg381 and Glu378. The residue is also acting as a Lewis acid, stabilising the build-up of negative charge in the transition state.

Literature References

Notes:PDB file appears to be homodimer; not mentioned in articles.
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