Vol. 40 No. 2, 2001
Purification and Characterization of Black Porgy Muscle Cu/Zn Superoxide Dismutase
Chi-Tsai Lin1,*, Tung-Liang Lee1, Kow-Jen Duan2 and Jong-Ching Su3
1Institute of Marine Biotechnology, National Taiwan Ocean University, Keelung, Taiwan 202
2Department of Bioengineering, Tatung University, Taipei, Taiwan 104
3Department of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan 106
Chi-Tsai Lin, Tung-Liang Lee, Kow-Jen Duan and Jong-Ching Su (2001) Superoxide
dismutase (SOD) has been proposed to be used as a bioindicator for
environmental impact assessment. From a survey of SOD activity in black
porgy, Acanthopagrus schlegeli,
we found that Cu/Zn SOD was distributed rather evenly in 6 tissues, and
in addition, only heart, liver, and testis had Mn SOD. We purified
Cu/Zn SOD from muscle to homogeneity by a procedure that includes
heating at 65°C and fractionation on 2 chromatographic columns. The
molecular mass of the native enzyme was 33 kDa and that of the subunit
mass, deduced from a cDNA sequence, was 15.85 kDa. Thus the native
enzyme appeared to be a homodimer. It had an N-terminal sequence of
VLKAVCVLKGAGQTTGVV. The specific activity was 3318 u/mg. The enzyme had
a broad optimum pH range of 5.8 to 11.2 and was resistant both to
proteolysis by trypsin and chymotrypsin and to heat denaturation.
The thermal inactivation rate constant of the enzyme at 80°C was
-0.0237 min-1 and the half life for inactivation was 27.8 min.
Key words: Black porgy, Acanthopagrus schlegeli, Cu/Zn superoxide dismutase, Thermal stability.
*Correspondence: Tel: 886-2-24622192 ext. 5513. Fax: 886-2-24622320. E-mail: B0220@mail.ntou.edu.tw