Purification and characterization of 3-isopropylmalate dehydrogenase from Thiobacillus thiooxidans

Hiroshi Kawaguchi, Kenji Inagaki, Hideyuki Matsunami, Yumi Nakayama, Tatsuo Tano, Hidehiko Tanaka

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


3-Isopropylmalate dehydrogenase was purified to homogeneity from the acidophilic autotroph Thiobacillus thiooxidans. The native enzyme was a dimer of molecular weight 40,000. The apparent Km values for 3-isopropylmalate and NAD+ were estimated to be 0.13 mM and 8.7 mM, respectively. The optimum pH for activity was 9.0 and the optimum temperature was 65°C. The properties of the enzyme were similar to those of the Thiobacillus ferrooxidans enzyme, expect for substrate specificity. T. thiooxidans 3-isopropylmalate dehydrogenase could not utilize malate as a substrate.

Original languageEnglish
Pages (from-to)459-461
Number of pages3
JournalJournal of Bioscience and Bioengineering
Issue number4
Publication statusPublished - Oct 2000


  • 3-isopropylmalate dehydrogenase
  • Purification
  • Thiobacillus thiooxidans

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Applied Microbiology and Biotechnology


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