Fig. 2.

Effect of the mutation of Tyr 422 to Asp in CYP2E1 on its ability to form the reduced–carbon monoxide (CO) complex when reduced with NADPH and for the CYP2E1 WT or the Y422D variant to inhibit CYP2B4 activity. (A) reduced CO spectrum of 0.5 nmol WT CYP2E1 (left) and the 0.5 nmol CYP2E1 Y422D variant (right). The reduced CO difference spectra were measured in the following reconstitutions, as described under Materials and Methods. Samples (i) and (iii) were chemically reduced with dithionite, whereas samples (ii) and (iv) were reconstituted with 1 nmol CPR and reduced by the addition of NADPH. (B) inhibition of CYP2B4 BNZ activity by CYP2E1 WT and the Y422D variant. The ability of the Y422D variant to inhibit CYP2B4 activity was assessed (open bars) and compared with WT CYP2E1 (filled bars), as described under Materials and Methods.