Functional assignment of Glu386 and Arg388 in the active site of l-galactono-¿-lactone dehydrogenase

N.G.H. Leferink, M.D.F. Jose, W.A.M. van den Berg, W.J.H. van Berkel

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15 Citations (Scopus)

Abstract

The flavoenzyme l-galactono-¿-lactone dehydrogenase (GALDH) catalyzes the terminal step of vitamin C biosynthesis in plants. Little is known about the catalytic mechanism of GALDH and related aldonolactone oxidoreductases. Here we identified an essential Glu–Arg pair in the active site of GALDH from Arabidopsis thaliana. Glu386 and Arg388 variants show high Km values for l-galactono-1,4-lactone and low turnover rates. Arg388 is crucial for the stabilization of the anionic form of the reduced FAD cofactor. Glu386 is involved in productive substrate binding. The E386D variant has lost its specificity for l-galactono-1,4-lactone and shows the highest catalytic efficiency with l-gulono-1,4-lactone
Original languageEnglish
Pages (from-to)3199-3203
JournalFEBS Letters
Volume583
Issue number19
DOIs
Publication statusPublished - 2009

Keywords

  • l-galactono-1,4-lactone dehydrogenase
  • flavocytochrome b(2)
  • cholesterol oxidase
  • oxygen reactivity
  • ascorbic-acid
  • vitamin-c
  • complex i
  • biosynthesis
  • plant
  • arabidopsis

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