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. Author manuscript; available in PMC: 2015 Jan 1.
Published in final edited form as: Arch Biochem Biophys. 2013 Nov 17;541:53–60. doi: 10.1016/j.abb.2013.11.001

FIGURE 6.

FIGURE 6

Effect of phospholipids on b5-stimulated catalysis of CYP3A4. Purified CYP3A4 (30 pmol) and POR were reconstituted with wild-type b5 or mutations D58G/D65G and E48G/E49G in the presence of various phospholipids at a P450:POR:b5 molar ratio of 1:2:3. Activities with reconstituted assays using two types of purified phosphatidyl choline (DLPC and DOPC) and three types of natural phospholipids (PC from porcine brain, containing fatty acyl groups 18:1 (33%), 16:0 (31%) and 18:0 (17%); PE from bovine brain, containing fatty acyl groups 18:1 (24%), 20:4 (19%) and 18:0 (16%); and PS from bovine brain, containing fatty acyl groups 18:0 (40%) and 18:1 (29%)) are shown. Incubations were carried out with 50 μM testosterone, and the formation of 6β-hydroxytestosterone was determined by HPLC analysis. Results are shown as the percentage activity compared to wild-type b5 values in PC+PS (=100%), means ± standard deviations from triplicate determinations. In the absence of b5, conversion to 6β-hydroxytestosterone is 0.4±0.1% under these conditions.