Fig. 5.

Characterization of the formation of M1 and M3 by CYP3A4 microsomes and reconstituted CYP3A4. Selected ion chromatograms of m/z 466 and m/z 468 recorded with Applied Biosystems API 4000 MS/MS, as described under Materials and Methods, are shown. Trans-(2S,4S,2′S)-ITZ was incubated with purified CYP3A4 reconstituted with P450 reductase (A and C) and CYP3A4 Supersomes (B and D), and the formation of M1 and M3 was followed at m/z 468 and m/z 466. The metabolite M3, m/z 466, was found in both enzyme systems; however, reduction to M1, m/z 468, occurred only in the Supersome incubation.