Figure 2.

Selectivity of RPE65 and DES1 inhibitors. (A) Chemical structures of RPE65 and DES1 inhibitors used in this study. (B) Inhibitory effects of retinoids, emixustat, and emixustat derivatives on DES1 activity in liver microsomes from 8-wk-old Lrat^−/− mice. Fenretinide, a known DES1 inhibitor, at a concentration of 10 µM suppressed DES1 activity nearly as well as heat treatment or omission of the required NADH cofactor. RPE65 inhibitors, in contrast, had less pronounced effects on activity. Assays shown here were performed at a fixed substrate concentration of 0.5 µM. Activity levels are normalized to that of the DMSO-only control samples. DMSO, at the concentration used in these assays (0.2% vol/vol), did not affect DES1 activity. (C) Inhibitory effects of retinoids, emixustat, and emixustat derivatives on 11-cis-retinol production in RPE microsomes. Compounds at final concentrations of 10 µM or 100 µM were incubated with RPE microsomes and 20 µM all-trans-retinol. Activities are normalized to DMSO-only treated samples. The bar graphs show mean values, and error bars represent SDs from at least three separate experiments.