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 journalArticlepeer-review

    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 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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