v5.1.0.3
Glycine data from LIS
Type | Family |
Description | 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 [ , , ]. 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 []. Inadequate levels of pyridoxal phosphate in the brain can cause neurological dysfunction, particularly epilepsy [].PLP enzymes exist in their resting state as a Schiff base, the aldehyde group of PLP forming a linkage with the ε-amino group of an active site lysine residue on the enzyme. The α-amino group of the substrate displaces the lysine ε-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 [ ].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 [ , ]. Among these enzymes are aromatic-L-amino-acid decarboxylase (L-dopa decarboxylase or tryptophan decarboxylase), which catalyses the decarboxylation of tryptophan to tryptamine []; tyrosine decarboxylase, which converts tyrosine into tyramine; histidine decarboxylase, which catalyses the decarboxylation of histidine to histamine []; L-aspartate decarboxylase, which converts aspartate to beta-alanine []; and phenylacetaldehyde synthase that catalyses the decarboxylation of L-phenylalanine to 2-phenylethylamine []. These enzymes belong to the group II decarboxylases [, ]. |
Short Name | PyrdxlP-dep_de-COase |