Dopachrome tautomerase is a zinc-containing enzyme.

Dopachrome tautomerase (DCT) catalyzes the conversion of L-dopachrome into 5,6-dihydroxyindole-2-carboxylic acid through the melanogenic biosynthetic pathway. This enzyme, also named TRP2, belongs to the family of the tyrosinase related proteins. The three members of the family contain two highly conserved metal-binding sites with three histidines on each. Tyrosinase has copper at its active site. It was assumed that although DCT might have copper in those metal binding sites, its active site could be related to other two putative iron-binding sites located in different positions. Based on apoDCT preparation with cyanide and reconstitution experiments, we propose that DCT have zinc instead of copper at the two metal-binding sites and that those sites actually correspond to the active site. The involvement of zinc, which cannot undergo redox reactions, accounts for the reaction that DCT catalyzes, a tautomerization versus the copper-mediated oxidations catalyzed by tyrosinase.