Biochemical characterization of psychrophilic Mn-superoxide dismutase from newly isolated Exiguobacterium sp. OS-77

Kyoshiro Nonaka, Ki Seok Yoon, Seiji Ogo

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)

Abstract

Many types of superoxide dismutases have been purified and characterized from various bacteria, however, a psychrophilic Mn-superoxide dismutase (MnSOD) has not yet been reported. Here, we describe the purification and the biochemical characterization of the psychrophilic MnSOD from Exiguobacterium sp. strain OS-77 (EgMnSOD). According to 16S rRNA sequence analysis, a newly isolated bacterium strain OS-77 belongs to the genus Exiguobacterium. The optimum growth temperature of the strain OS-77 is 20 °C. The EgMnSOD is a homodimer of 23.5 kDa polypeptides determined by SDS-PAGE and gel filtration analysis. UV-Vis spectrum and ICP-MS analysis clearly indicated that the homogeneously purified enzyme contains only a Mn ion as a metal cofactor. The optimal reaction pH and temperature of the enzyme were pH 9.0 and 5 °C, respectively. Notably, the purified EgMnSOD was thermostable up to 45 °C and retained 50 % activity after 21.2 min at 60 °C. The differential scanning calorimetry also indicated that the EgMnSOD is thermostable, exhibiting two protein denaturation peaks at 65 and 84 °C. The statistical analysis of amino acid sequence and composition of the EgMnSOD suggests that the enzyme retains psychrophilic characteristics.

Original languageEnglish
Pages (from-to)363-373
Number of pages11
JournalExtremophiles
Volume18
Issue number2
DOIs
Publication statusPublished - Mar 2014

All Science Journal Classification (ASJC) codes

  • Microbiology
  • Molecular Medicine

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