(A) Structures of dopachrome methyl ester
(1), a chromogenic substrate for the measurement of MIF
enzymatic activity, and its tautomerized, colorless product
(2). (B) Structures of acetaminophen
(3) and the oxidation products
N-acetyl-p-benzoquinone imine (NAPQI,
4) and
N-acetyl-3-hydroxy-p-benzoquinone imine
(HQ, 6), which are related structurally to 1.