THE EXTRACTION AND PROPERTIES OF SUPEROXIDE-DISMUTASE FROM PORCINE BLOOD

Crude superoxide dismutase (SOD) was prepared by extraction with chlor oform-ethanol, centrifugation and acetone precipitation. The specific activity of the SOD was 1570 units mg(-1), and an unusual ultraviolet spectrum with maximum absorbance at 256.4 nm was observed. When the SO D was kept at 40, 50 and 60 degrees C for 10 min, it showed little los s of stability but it retained only 95, 69, 45 and 2.5% of its origina l activity after holding at 60, 70, 75, and 80 degrees C for 5 min., r espectively. When cupric ions were added, the thermostability of SOD w as enhanced. When the extracted SOD was kept at -23, 4, 25 and 30 degr ees C for 20 weeks, the relative activity retained was 76, 67, 26 and 16%, respectively. Using the sensitive test with cyanide and hydrogen peroxide, the acrylamide gel of the SOD showed this enzyme was of the Cu/Zn type. The molecular weights of the holoenzyme and its subunits, estimated by SDS-polyacrylamide gel electrophoresis, were approximatel y 31 and 15 kD, respectively. (C) 1997 Elsevier Science Ltd.