Purification and characterization of glutathione transferase from psoriatic skin.

The glutathione transferases (GSTs) comprise a family of enzymes that catalyze the conjugation of glutathione with certain hydrophobic compounds, bind various hydrophobic compounds, and have selenium-independent glutathione peroxidase activity. Of the four classes of GST, the pi class is the only one present in keratinocytes, and pi-class GST is elevated in psoriatic epidermis. We have purified and characterized GST from psoriatic scales. Immunoreactivity was observed with pi class antisera, and amino terminal sequencing showed identity with GST from human placenta and cultured human keratinocytes. We conclude that the majority of GST activity in psoriatic skin is due to a pi-class isoenzyme, and pi-class GST may represent an index for hyperproliferation.