Activities | Families | Sequences | Fold types | References | Help
B6db activities: 5.1.1.18

5.1.1.18
Description Serine racemase
Catalyzed reaction L-Serine = D-Serine
Cofactor Pyridoxal-phosphate.
Comments A pyridoxal-phosphate protein that is highly selective for L-serine as substrate. D-Serine is found in type-II astrocytes in mammalian brain, where it appears to be an endogenous ligand of the glycine site of N-methyl-D-aspartate (NMDA) receptors. The reaction can also occur in the reverse direction but does so more showly at physiological serine concentrations.
Validated eukaryotic enzymes (from metazoa and plants) are similar in sequence to serine ammonia-lyases (4.3.1.17), and in fact they often catalyze dehydration of serine to pyruvate in addition to serine racemization.

In bacteria, amino acid racemization is usually carried out by fold-type III enzymes (that we have grouped in the 5.1.1.1 family). In bacteria amino acid racemization is usually carried out by fold-type III enzymes (that we have grouped in the 5.1.1.1 family).
One fold-type II bacterial enzyme with some serine racemase activity (WP_013961474 from Roseobacter litoralis; see Kubota et al. 2016, Microbiology 162 53-61) is probably acting physiologically as an erythro-3-hydroxy-D-aspartate ammonia-lyase (family bhcb), as suggested by the genomic context.

An archaeal enzyme (from Pyrobaculum) that has been characterized and annotated as a Ser racemase, is in fact a promiscuous catalyst, carrying out both the deamination of L-Ser and L-Thr and, less efficiently, the racemization of the same amino acids.
For homology reasons, this sequence has been included in family 4.3.1.19 (L-Thr deaminase).

PDB 3L6R; 1V71;
Organisms -Archea -Plants -Metazoa -Human
 
 
Links Enzyme (activities) 5.1.1.18
BRENDA (activities) 5.1.1.18
KEGG (pathways) 5.1.1.18
PLPMDB (PLP mutants) 5.1.1.18
 
References Articles on 5.1.1.18
 
last changed 2019/11/20 17:12

B6db activities