Vol. 40 No. 2, 2001

Purification and Characterization of Black Porgy Muscle Cu/Zn Superoxide Dismutase

Chi-Tsai Lin^1,*, 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