Putative phospholipid hydroperoxide glutathione peroxidase from Antrodia camphorata

Glutathione Peroxidases (GPxs) play important roles in antioxidation. A cDNA (Ac-PHGPx, 764 bp) encoding a putative phospholipid hydroperoxide glutathione peroxidase (PHGPx) from Antrodia camphorata has been cloned. The deduced amino acid sequence is conserved among the reported GPxs. To characterize the Ac-PHGPx, the coding region was subcloned into pYEX-S1 and transformed into Saccharomyces cerevisiae. The recombinant 6His-tagged Ac-PHGPx was expressed and purified by Ni2+-nitrilotriacetic acid Sepharose. The purified enzyme showed a predominant band with molecular mass of ∼18 kDa on 12% SDS–PAGE. The enzyme retained 50% activity at 60 °C for 8 min. The enzyme was most active at pH 9. The enzyme showed 42% activity after incubation with trypsin at 37 °C for 40 min. In addition, the ability of Ac-PHGPx to protect intact supercoiled plasmid DNA from OH induced nicking was demonstrated.