Serine racemases from barley, Hordeum vulgare L., and other plant species represent a distinct eukaryotic group: gene cloning and recombinant protein characterization.
Several d-amino acids have been identified in plants. However, the biosynthetic pathway to them is unclear. In this study, we cloned and sequenced a cDNA encoding a serine racemase from barley which contained an open reading frame encoding 337 amino acid residues. The deduced amino acid sequence showed significant identity to plant and mammalian serine racemases and contained conserved pyridoxal 5-phosphate (PLP)-binding lysine and PLP-interacting amino acid residues. The purified gene product catalyzed not only racemization of serine but also dehydration of serine to pyruvate. The enzyme requires PLP and divalent cations such as Ca(2+), Mg(2+), or Mn(2+), but not ATP, whereas mammalian serine racemase activity is increased by ATP. In addition to the results regarding the effect of ATP on enzyme activity and the phylogenetic analysis of eukaryotic serine racemases, the antiserum against Arabidopsis serine racemase did not form a precipitate with barley and rice serine racemases. This suggests that plant serine racemases represent a distinct group in the eukaryotic serine racemase family and can be clustered into monocot and dicot types.
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CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL GENE-N GENE-N GENE-Y GENE-N GENE-N GENE-N GENE-Y GENE-N GENE-N
serine serine serine amino acid amino acid serine pyridoxal 5-phosphate PLP lysine PLP amino acid serine serine pyruvate PLP Ca(2+) Mg(2+) Mn(2+) ATP serine ATP ATP d-amino acids serine serine serine Serine serine racemases serine racemase serine racemase serine racemases serine racemase serine racemases Arabidopsis serine racemase serine racemases Serine racemases