Pathways & interactions
Pyridoxal phosphate-dependent decarboxylase (IPR002129)
Short name: PyrdxlP-dep_de-COase
Overlapping homologous superfamilies
- Pyridoxal phosphate-dependent transferase, major domain (IPR015421)
- Pyridoxal phosphate-dependent transferase (IPR015424)
- Pyridoxal phosphate-dependent decarboxylase (IPR002129)
Pyridoxal phosphate is the active form of vitamin B6 (pyridoxine or pyridoxal). Pyridoxal 5'-phosphate (PLP) is a versatile catalyst, acting as a coenzyme in a multitude of reactions, including decarboxylation, deamination and transamination [PMID: 8690703, PMID: 7748903, PMID: 15189147]. PLP-dependent enzymes are primarily involved in the biosynthesis of amino acids and amino acid-derived metabolites, but they are also found in the biosynthetic pathways of amino sugars and in the synthesis or catabolism of neurotransmitters; pyridoxal phosphate can also inhibit DNA polymerases and several steroid receptors [PMID: 17109392]. Inadequate levels of pyridoxal phosphate in the brain can cause neurological dysfunction, particularly epilepsy [PMID: 16763894].
PLP enzymes exist in their resting state as a Schiff base, the aldehyde group of PLP forming a linkage with the epsilon-amino group of an active site lysine residue on the enzyme. The alpha-amino group of the substrate displaces the lysine epsilon-amino group, in the process forming a new aldimine with the substrate. This aldimine is the common central intermediate for all PLP-catalysed reactions, enzymatic and non-enzymatic [PMID: 15581583].
A number of pyridoxal-dependent decarboxylases share regions of sequence similarity, particularly in the vicinity of a conserved lysine residue, which provides the attachment site for the pyridoxal-phosphate (PLP) group [PMID: 8181483, PMID: 2124279]. Among these enzymes are aromatic-L-amino-acid decarboxylase (L-dopa decarboxylase or tryptophan decarboxylase), which catalyses the decarboxylation of tryptophan to tryptamine [PMID: 8889823]; tyrosine decarboxylase, which converts tyrosine into tyramine; histidine decarboxylase, which catalyses the decarboxylation of histidine to histamine [PMID: 2300558]; and L-aspartate decarboxylase, which converts aspartate to beta-alanine [PMID: 24415726]. These enzymes belong to the group II decarboxylases [PMID: 8181483, PMID: 8889823].
- PF00282 (Pyridoxal_deC)