Purification, N-terminal amino acid sequence and partial characterization of a Cu,Zn superoxide dismutase from the pathogenic fungus Aspergillus fumigatus.
A superoxide dismutase (SOD) has been purified to homogeneity from the fungal pathogen Aspergillus fumigatus using a combination of cell homogenization, isoelectric focusing and gel filtration FPLC. The N-terminal amino acid sequence of the purified enzyme demonstrated substantial homology to known Cu,Zn superoxide dismutases for a range of organisms, including Neurospora crassa and Saccharomyces cerevisiae. The enzyme subunit has a pI of 5.9, a relative molecular mass of 19 kDa and a spectral absorbance maximum of 550nm. The non reduced enzyme has a relative molecular mass of 95 kDa. The enzyme remained active after prolonged incubation at 70 degrees C and was pH insensitive in the range 7-11. Potassium cyanide and diethyldithiocarbamate, known Cu,Zn SOD inhibitors, caused inhibition of the purified enzyme at working concentrations of 0.25 mM, whilst sodium azide and o-phenanthroline demonstrated inhibition at higher concentrations (10-30 mM). SOD activity was also detectable in culture filtrate of A. fumigatus. This enzyme may have a potential role as a virulence factor in the avoidance of neutrophil and phagocyte oxidative burst killing mechanisms.
Holdom
M D
MD
Dermatology Unit, St. Johns Institute of Dermatology, Guy's Hospital, London.
Hay
R J
RJ
Hamilton
A J
AJ
D000595:Amino Acid Sequence; D001232:Aspergillus fumigatus / Q000201:enzymology*; D004795:Enzyme Stability; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D013482:Superoxide Dismutase / Q000737:chemistry / Q000302:isolation & purification*
D013482:Superoxide Dismutase