Ingelman-Sundberg M, Hagbjörk A L, Ueng Y F, Yamazaki H, Guengerich F P
Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.
Biochem Biophys Res Commun. 1996 Apr 16;221(2):318-22. doi: 10.1006/bbrc.1996.0593.
CYP3A4 represents the most important form of human cytochrome P450 active in drug metabolism. Reconstitution of this enzyme has in the past been a major problem. Using purified cDNA-expressed CYP3A4 incorporated into membranous vesicles made from microsomal phospholipids, rates of nifedipine and testosterone oxidation of about 60 nmol/nmol P450/min were achieved, whereas similar reconstitution into dilauroyl-phosphatidylcholine micelles was unsuccessful. A higher Vmax for nifedipine oxidation was obtained in negatively charged vesicles as compared to neutral membranes, whereas the membrane charge did not influence the Km. It is concluded that the native function of CYP3A4 requires a negatively charged microsomal membrane.
CYP3A4是人体细胞色素P450中在药物代谢方面最具活性的一种形式。过去，该酶的重组一直是个主要问题。利用掺入由微粒体磷脂制成的膜泡中的纯化的cDNA表达的CYP3A4，硝苯地平氧化速率和睾酮氧化速率达到了约60 nmol/nmol P450/分钟，而在二月桂酰磷脂酰胆碱微团中进行类似重组则未成功。与中性膜相比，在带负电荷的膜泡中硝苯地平氧化的Vmax更高，而膜电荷不影响Km。得出的结论是，CYP3A4的天然功能需要带负电荷的微粒体膜。
