FIGURE 4.

Stereospecificity. Stereoselectivity was studied by enzyme assays (A and B) and cellular metabolism assays (C and D). PSI-352707 product formation was followed by incubating PSI-7851 (□), PSI-7976 (○), or PSI-7977 (△) with human recombinant CatA (A) or CES1 (B). Time-dependent formation of PSI-7409 (active triphosphate form) in clone A cells (C) or primary human hepatocytes (HHPC) (D) was by incubating with PSI-7851 (□), PSI-7976 (○), or PSI-7977 (△). See “Experimental Procedures” for the experimental conditions.