Purification and characterization of manganese superoxide dismutase from Ganoderma microsporum

Manganese superoxide dismutase (Mn-SOD) in the mycelium of Ganoderma microsporum was purified to homogeneity by heat treatment at 70 degrees C, ammonium sulfate fractionation, DEAE-52 anion-exchange chromatography, and Sephacryl SH-200 chromatography. The molecular mass of its native form was estimated to be 98 kD by size-exclusion chromatography. This enzyme is tetrameric composed of four subunits of equal size of 25 kD. The pI of this purified Mn-SOD was located at pH 6.34 and 5.06 by isoelectric focusing. Comparisons of 17 amino acids from the N-terminus of Mn-SOD subunit with the derived amino acid sequences from the reported Mn-SOD cDNA clones of other sources indicated a high degree of homology among the Ganoderma genus but the Mn-SOD from G. microsporum showed a high variation when compared with other organisms.