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Catalytic Site Atlas

CSA LITERATURE entry for 1kqc

E.C. nameOXYGEN-INSENSITIVE NAD(P)H NITROREDUCTASE
SpeciesEnterobacter cloacae (Bacteria)
E.C. Number (IntEnz) 1.6.6.-
CSA Homologues of 1kqc
CSA Entries With UniProtID
CSA Entries With EC Number 1.6.6.-
PDBe Entry 1kqc
PDBSum Entry 1kqc
MACiE Entry 1kqc

Literature Report

IntroductionNitroreductase (NR) is a member of a group of enzymes that reduce a broad range of nitroaromatic compounds and has potential uses in chemotherapy and bioremediation. The substrate binds over the pyrimidine and central rings of the flavin. A portion of helix H6 can flex to accommodate the differently sized inhibitors suggesting a mechanism for accommodating varied substrates. this enzyme was first isolated from bacteria growing in a weapons storage dump, and can reduce trinitrotoluene.
MechansimThis enzyme derives reducing equivalents from NADH, NADPH, or other nicotinamides by means of a flavin mononucleotide cofactor (FMN). The reaction proceeds by reduction of the nitro group of the substrate, forming a hydroxylamine product in a ping-pong Bi-Bi reaction pathway.
Prior to the substrate binding, FMN accepts a hydride from NADH onto N5. NADH then leaves as NAD+. The resultant negative charge is transferred through the delocalised system onto O3 where electrostatic interactions with K14 and K74 stabilise it. The nitro group to be attacked stacks above N5 of the re face of FMN which then transfers the hydride. At the same time the nitro group accepts a proton from water. The resultant -N(OH)2 group spontaneously eliminates water. A second hydride is passed to FMN by NADH, the charge again moves to O3 where it is best stabilised followed by transfer of the hydride to the nitroso group which simultaneously accepts a proton from water onto the oxygen, leading to the product, hydroxylamine.

Catalytic Sites for 1kqc

Annotated By Reference To The Literature - Site 5 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
LysA7474macie:sideChainElectrostatic stabilisation of charge build up on the FMN at O3 during hydride transfer.
LysA1414macie:sideChainElectrostatic stabilisation of charge build up on the FMN at N1 and O3 during hydride transfer.

Annotated By Reference To The Literature - Site 6 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
LysB7474macie:sideChainElectrostatic stabilisation of charge build up on the FMN at O3 during hydride transfer.
LysB1414macie:sideChainElectrostatic stabilisation of charge build up on the FMN at N1 and O3 during hydride transfer.

Annotated By Reference To The Literature - Site 7 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
LysC7474macie:sideChainElectrostatic stabilisation of charge build up on the FMN at O3 during hydride transfer.
LysC1414macie:sideChainElectrostatic stabilisation of charge build up on the FMN at N1 and O3 during hydride transfer.

Annotated By Reference To The Literature - Site 8 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
LysD7474macie:sideChainElectrostatic stabilisation of charge build up on the FMN at O3 during hydride transfer.
LysD1414macie:sideChainElectrostatic stabilisation of charge build up on the FMN at N1 and O3 during hydride transfer.

Literature References

Notes:
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