Molecular and biochemical characterization of a serine racemase from Arabidopsis thaliana

Yoshiyuki Fujitani, Nobuyoshi Nakajima, Koji Ishihara, Tadao Oikawa, Kazutoshi Ito, Manabu Sugimoto

Research output: Contribution to journalArticle

45 Citations (Scopus)

Abstract

A cDNA encoding a homolog of mammalian serine racemase, a unique enzyme in eukaryotes, was isolated from Arabidopsis thaliana and expressed in Escherichia coli cells. The gene product, of which the amino acid residues for binding pyridoxal 5′-phosphate (PLP) are conserved in this as well as mammalian serine racemases, catalyzes not only serine racemization but also dehydration of serine to pyruvate. The enzyme is a homodimer and requires PLP and divalent cations, Ca2+, Mg2+, Mn2+, Fe2+, or Ni2+, at alkaline pH for both activities. The racemization process is highly specific toward l-serine, whereas l-alanine, l-arginine, and l-glutamine were poor substrates. The Vmax/Km values for racemase activity of l- and d-serine are 2.0 and 1.4 nmol/mg/min/mM, respectively, and those values for l- and d-serine on dehydratase activity are 13 and 5.3 nmol/mg/min/mM, i.e. consistent with the theory of racemization reaction and the specificity of dehydration toward l-serine. Hybridization analysis showed that the serine racemase gene was expressed in various organs of A. thaliana.

Original languageEnglish
Pages (from-to)668-674
Number of pages7
JournalPhytochemistry
Volume67
Issue number7
DOIs
Publication statusPublished - Apr 1 2006

Keywords

  • Arabidopsis thaliana
  • D-Amino acid
  • Pyridoxal 5′-phosphate
  • Serine racemase

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Plant Science
  • Horticulture

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