Purification and characterization of black porgy muscle Cu/Zn superoxide dismutase

Purification and characterization of black porgy muscle Cu/Zn superoxide di smutase. Zoological Studies 40(2): 84-90. Superoxide dismutase (SOD) has be en proposed to be used as a bioindicator for environmental impact assessmen t. From a survey of SOD activity in black porgy, Acanthopagrus schlegeli, w e found that Cu/Zn SOD was distributed rather evenly in 6 tissues, and in a ddition, only heart, liver, and testis had Mn SOD. We purified Cu/Zn SOD fr om muscle to homogeneity by a procedure that includes heating at 65 degrees 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 activit y was 3318 mu /mg. The enzyme had a broad optimum pH range of 5.8 to 11.2 a nd was resistant both to proteolysis by trypsin and chymotrypsin and to hea t denaturation. The thermal inactivation rate constant of the enzyme at 80 degreesC was -0.0237 min(-1) and the half life for inactivation was 27.8 mi n.