Purification and characterization of a glutathione S-transferase from the fungus Cunninghamella elegans

Abstract

Cunninghamella elegans grown on Sabouraud dextrose broth had glutathione S-transferase (GST) activity. The enzyme was purified 172-fold from the cytosolic fraction (120 000×g) of the extract from a culture of C. elegans, using Q-Sepharose ion exchange chromatography and glutathione affinity chromatography. The GST showed activity against 1-chloro-2,4-dinitrobenzene, 1,2-dichloro-4-nitrobenzene, 4-nitrobenzyl chloride, and ethacrynic acid. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis gel filtration chromatography revealed that the native enzyme was homodimeric with a subunit of Mr 27 000. Comparison by Western blot analysis implied that this fungal GST had no relationship with mammalian α-, μ-, and π-class GSTs, although it showed a small degree of cross-reactivity with a θ-class GST. The N-terminal amino acid sequence of the purified enzyme showed no significant homology with other known GSTs.