Alanine racemase from an acidophile, acidiphilium organovorum: Purification and characterization

Teck Keong Seow, Kenji Inagaki, Takashi Tamura, Kenji Soda, Hidehiko Tanaka

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12 Citations (Scopus)

Abstract

An alanine racemase (EC 5.1.1.1) from an acidophilic heterotrophic bacterium, Acidiphilium organovorum 13H, was purified and characterized. The enzyme had a dimeric structure with identical subunits of M, 33,000 each. Although A. organovorum 13H is an acidophile, the enzyme had its maximum velocity at pH 9, corresponding to its location in the cytoplasm. Activity was maximum between 50 and 60°C. For an enzyme from a mesophile, it was stable to heat, showing no loss of activity after a 30-min incubation at 65°C. The enzyme needed pyridoxal 5′. phosphate (PLP) as a cofactor for its activity, as seen from the loss of activity upon dialysis against PLP-free buffer containing hydroxylamine and its absorption maximum at 420 nm. Activity was ihhibited by common inhibitors of PLP-dependent enzymes. PLP content studies found that 1 mole of enzyme contained 2 moles of PLP. The enzyme catalyzed the symmetric reversible racemization of alanine exclusively.

Original languageEnglish
Pages (from-to)242-247
Number of pages6
JournalBioscience, Biotechnology and Biochemistry
Volume62
Issue number2
DOIs
Publication statusPublished - Jan 1 1998

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Keywords

  • Acidiphilium organovorum
  • Acidophile
  • Alanine racemase
  • Pyridoxal 5′-phosphate

ASJC Scopus subject areas

  • Biotechnology
  • Analytical Chemistry
  • Biochemistry
  • Applied Microbiology and Biotechnology
  • Molecular Biology
  • Organic Chemistry

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