Binding of epi-dihydrolanosterol and steady-state kinetics of oxidation of epi-dihydrolanosterol to epi-dihydro FF-MAS.A, Kd 0.014 (±0.031) μM. B, kcat 0.42 ± 0.03 s−1, Km 2.0 ± 0.4 μM. Rates are presented on the y-axis as nmol product (epi-dihydro FF-MAS) formed min−1 (nmol P450)−1 in (B). Incubations were run in triplicate, and the means (±SD) were calculated and plotted. The linear regression fits include the Prism error estimates for internal fitting (SE). FF-MAS, follicular fluid meiosis-activating sterol ((4β,5α)-4,4-dimethyl-cholesta-8,14,24-trien-3-ol).