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Ornithine decarboxylase

ornithine decarboxylase
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Ornithine decarboxylase dimer, Human
Identifiers
EC number 4.1.1.17
CAS number 9024-60-6
Databases
IntEnz IntEnz view
BRENDA BRENDA entry
ExPASy NiceZyme view
KEGG KEGG entry
MetaCyc metabolic pathway
PRIAM profile
PDB structures RCSB PDB PDBe PDBsum
Gene Ontology AmiGO / EGO
ornithine decarboxylase
Identifiers
Symbol ODC1
Entrez 4953
HUGO 8109
OMIM 165640
RefSeq NM_002539
UniProt P11926
Other data
EC number 4.1.1.17
Locus Chr. 2 p25

The enzyme ornithine decarboxylase (ODC) catalyzes the decarboxylation of ornithine (a product of the urea cycle) to form putrescine. This reaction is the committed step in polyamine synthesis. In humans, this protein has 461 amino acids and forms a homodimer.

Lysine 69 on ornithine decarboxylase (ODC) binds the cofactor pyridoxal phosphate to form a Schiff base. Ornithine displaces the lysine to form a Schiff base attached to ODC, which decarboxylates to form a quinoid intermediate. This intermediate rearranges to form a Schiff base attached to putrescine, which is attacked by lysine to release putrescine product and reform PLP-bound ODC.

ornithine decarboxylase mechanism

This is the first step and the rate-limiting step in humans for the production of polyamines, compounds required for cell division.

The active form of ornithine decarboyxlase is a homodimer. Each monomer contains a barrel domain, consisting of an alpha-beta barrel, and a sheet domain, composed of two beta-sheets. The domains are connected by loops. The monomers connect to each other via interactions between the barrel of one monomer and the sheet of the other. Binding between monomers is relatively weak, and ODC interconverts rapidly between monomeric and dimeric forms in the cell.


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Wikipedia

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