Figure 1.
(A) Structure of dopachrome methyl ester, a chromogenic substrate used in enzymatic assays of MIF, and its tautomerized colorless product. (B) Relationship between seminal fluid MIF concentrations and the dopachrome decolorizing rate (tautomerase activity) (n = 18, r2 = 0.88); Seminal fluid exhibited dopachrome tautomerase activity. (C) MIF tautomerase activity in seminal fluids obtained from normozoospermic subjects (controls, n = 27) and patients with abnormal sperm parameters (n = 68, P < 0.001).