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Catalytic Site Atlas Version 2.2.12
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CSA entry for 1b5q
Original Entry
Title:
Oxidoreductase
Compound:
Polyamine oxidase
Mutant:
No
UniProt/Swiss-Prot:
O64411-PAO_MAIZE
EC Class:
1.5.3.11
Other CSA Entries:
Overview of all sites for 1b5q
Homologues of 1b5q
Entries for UniProt/Swiss-Prot: O64411
Entries for EC: 1.5.3.11
Other Databases:
PDB entry: 1b5q
PDBsum entry: 1b5q
UniProt/Swiss-Prot: O64411
IntEnz entry: 1.5.3.11
Literature Report:
Introduction:
Polyamine oxidase is able to catalyse the oxidation of the secondary amino groups of polyamines to their corresponding imino forms, using FAD as a cofactor coupled to eventual reduction of H2O2 to form water. The product of the reaction depends on the initial starting material; for example mammalian polyamine oxidase can convert spermidine to putrescine. Polyamines bind DNA and regulate transcription and translation, thus play roles in cell differentiation and multiplication, causing them to be implicated in the development of certain forms of cancer. As a result the enzyme is of interest as a drug target. Despite different physiological roles, mammalian, plant and bacterial forms of the enzyme show significant sequence and structural homology, and polyamine oxidases also show homology to monoamine oxidases, suggesting a common catalytic mechanism.
Mechanism:
The reaction is believed to proceed through nucleophilic attack from the amino group, deprotonated by Glu 62, on the C4a of FAD. This leads to a covalent adduct which collapses, assisted by proton transfer from the alpha carbon to the N5 of FAD via a water molecule, to give the product imine.
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Found by:
Literature reference 

ResidueChainNumberUniProt numberFunctional part FunctionTargetDescription
GLUA 62 90Sidechain
Acid/baseSubstrate
Acts as general base to remove proton from the nucleophilic amino group of the substrate.
Evidence from paper Evidence concerns Evidence type
PubMed ID 15865452 Current protein Kinetic studies
PubMed ID 11258887 Current protein Residue is positioned appropriately (ligand position known)

ResidueChainNumberUniProt numberFunctional part FunctionTargetDescription
FADC 579 0
ElectrophileSubstrate
Electron donor/acceptorSubstrate
Acts as an electrophile in the nucleophilic attack of the substrate amino group thus accepts electrons from the nitrogen which can then be passed to H2O2.
Evidence from paper Evidence concerns Evidence type
PubMed ID 11258887 Current protein Ligand is essential for catalysis
PubMed ID 11258887 Current protein Residue is positioned appropriately (ligand position known)
Notes:
There are alternative mechanistic possibilities described in 15865452
References:
1
Structural bases for inhibitor binding and catalysis in polyamine oxidase.
C. Binda and R. Angelini and R. Federico and P. Ascenzi and A. Mattevi
Biochemistry 40, (9) 2766-76, (2001).
11258887
2
Mechanistic studies of mouse polyamine oxidase with N1,N12-bisethylspermine as a substrate.
M. Royo and P. F. Fitzpatrick
Biochemistry 44, (18) 7079-84, (2005).
15865452
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