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Catalytic Site Atlas Version 2.2.12
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CSA entry for 1knp
Original Entry
Title:
Oxidoreductase
Compound:
L-aspartate oxidase
Mutant:
Yes
UniProt/Swiss-Prot:
P10902-NADB_ECOLI
EC Class:
1.4.3.16
Other CSA Entries:
Overview of all sites for 1knp
Homologues of 1knp
Entries for UniProt/Swiss-Prot: P10902
Entries for EC: 1.4.3.16
Other Databases:
PDB entry: 1knp
PDBsum entry: 1knp
UniProt/Swiss-Prot: P10902
IntEnz entry: 1.4.3.16
Literature Report:
Introduction:
L-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.
Mechanism:
L-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.
Sites:

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Found by:
Literature reference 

ResidueChainNumberUniProt numberFunctional part FunctionTargetDescription
800 0
Substrate
Accepts a hydride from L-aspartate. Donates a hydride to either fumarate or oxygen.
Evidence from paper Evidence concerns Evidence type
PubMed ID 11863440 Current protein Residue is positioned appropriately (ligand position known)
PubMed ID 11863440 Current protein Ligand is essential for catalysis

ResidueChainNumberUniProt numberFunctional part FunctionTargetDescription
ARGA 290 290Sidechain
Acid/baseSubstrate
Acts 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.
Evidence from paper Evidence concerns Evidence type
PubMed ID 11863440 Current protein Mutagenesis of residue
PubMed ID 11863440 Current protein Residue is positioned appropriately (ligand position known)

ResidueChainNumberUniProt numberFunctional part FunctionTargetDescription
HISA 351 351Sidechain
ElectrostaticSubstrate
Acts to stabilise the negatively charged intermediate.
Evidence from paper Evidence concerns Evidence type
PubMed ID 11863440 Current protein Residue is positioned appropriately (ligand position known)

ResidueChainNumberUniProt numberFunctional part FunctionTargetDescription
LEUA 386 386Sidechain
ElectrostaticSubstrate
Acts to stabilise the negatively charged intermediate.
Evidence from paper Evidence concerns Evidence type
PubMed ID 11863440 Current protein Residue is positioned appropriately (ligand position known)
PubMed ID 11863440 Current protein Mutagenesis of residue
Notes:
Other possible catalytic residues are His 244 and Arg 263, but there is not enough evidence for a definite assignment.
References:
1
Structure of FAD-bound L-aspartate oxidase: insight into substrate specificity and catalysis.
R. T. Bossi and A. Negri and G. Tedeschi and A. Mattevi
Biochemistry 41, (9) 3018-24, (2002).
11863440
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