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Search The CSA
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Catalytic Site Atlas

CSA LITERATURE entry for 1knp

E.C. nameL-aspartate oxidase
SpeciesEscherichia coli (Bacteria)
E.C. Number (IntEnz) 1.4.3.16
CSA Homologues of 1knp
CSA Entries With UniProtID P10902
CSA Entries With EC Number 1.4.3.16
PDBe Entry 1knp
PDBSum Entry 1knp
MACiE Entry 1knp

Literature Report

IntroductionL-aspartate oxidase (LASPO) is a flavo enzyme from Escherichia coli. It is unusual as it can use both oxygen and fumarate as electron acceptors for FAD oxidation, which means it is both aerobic and anaerobic. LASPO is an FAD dependent enzyme which catalyses the oxidation of L-aspartate into iminoaspartate. This is the first step in the bacterial synthesis of NAD+, and is a useful target for drug design, as this pathway is not present in mammals.
MechansimL-aspartate oxidation 1. Arg 290 acts as a base by deprotonating C3 of L-aspartate. 2. Arg 386 and His 351 stabilise the negative charge on the O4 oxygen atoms. 3. FAD then accepts a hydride from C2 of L-aspartate (and most likely then accepts a proton from the solvent to form FADH2.)
FADH- oxidation (for fumarate) 1. FADH- donates a hydride to the C2 atom of fumarate. 2. The negative charge is localised on the O4 atoms which are stabilised by Arg 386 and His 351. 3. The C4 carbonyl is reformed, and Arg 290 donates a proton to the C3 atom, forming succinate.
Reaction

Catalytic Sites for 1knp

Annotated By Reference To The Literature - Site 1 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
LeuA386386macie:sideChainActs to stabilise the negatively charged intermediate.
ArgA290290macie:sideChainActs as a base and deprotonates the C3 atom of L-aspartate. Acts as an acid in its protonated form, and donates a proton to the C3 atom of fumerate.
HisA351351macie:sideChainActs to stabilise the negatively charged intermediate.

Literature References

Notes:Other possible catalytic residues are His 244 and Arg 263, but there is not enough evidence for a definite assignment.
Bossi RT
Structure of FAD-bound L-aspartate oxidase: insight into substrate specificity and catalysis.
Biochemistry 2002 41 3018-3024
PubMed: 11863440
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