GSTZ1, also known as maleylacetoacetate isomerase, is an enzyme that belongs to glutathione Stransferase (GSTs) super-family. This enzyme acts by catalyzing the reaction of glutathione with an acceptor molecule to form an S-substituted glutathione (S=sulfur). The reactions utilizing glutathione contribute the transformation of a wide variety of electrophiles, including reactive products of lipid, protein, carcinogens, therapeutic drugs, environmental toxins, and products of oxidative stress.