Basic approach for good prescribing: Post-translational modulation of activities of drug-metabolizing enzymes

研究了药物代谢酶活性的翻译后调节。以下是该项目的成果。1)CYP 1A 2和CYP 2C 9能够修饰UGT 2B 7功能。然而，这些P450调节UGT 2B 7功能的潜在机制似乎与CYP 3A 4不同。2)通过免疫沉淀、重叠试验和使用交联剂1-乙基-3-[3-（二甲氨基）丙基]碳二亚胺（EDC）进行交联，更详细地证明了CYP 3A 4-UGT 2B 7的结合。3)确定了在与UGT 2B 7相互作用中发挥作用的CYP 3A 4候选区域。4)酮康唑通过竞争性和非竞争性抑制等新机制抑制吗啡UGT。5)在大鼠中也发现了P450-UGT的关联。有人认为，这种相互作用是保守的物种。6)酰基辅酶A作为UGT的内源性激活剂发挥作用。7)存在于内质网内的许多细胞核苷酸调节UGT功能。这些物质与UGT上的一个共同的变构位点结合，从而降低了UGT的催化功能，提示P450与UGT之间存在功能性相互作用。此外，内源性调节剂对UGT也可能是重要的。有必要进一步研究以阐明CYP 3A 4和UGT 2B 7之间的相互作用对UGT 2B 7体内催化反应的影响。

Post-translational modulation of activities of drug-metabolizing enzymes was studied. Followings are outcomes from this project. 1) CYP1A2 and CYP2C9 have ability to modify UGT2B7 function. However, the mechanism(s) underlying the modulation of UGT2B7 function by these P450s seems to differ from that by CYP3A4. 2) CYP3A4-UGT2B7 association was demonstrated in more detail by means of immunoprecipitation, overlay assay and cross-linking with a cross-linker, 1-ethyl-3-[3- (dimethylamino)propyl]carbodiimide (EDC). 3) The candidate region of CYP3A4 which plays a role in the interaction with UGT2B7 was determined. 4) Ketoconazole exerts its inhibitory effect on morphine UGT by novel mechanisms involving competitive and noncompetitive inhibition. 5) P450-UGT association was also found in rats. It was suggested that such interaction is conserved from species to species. 6) Acyl-CoAs play a role as an endogenous activator of UGTs. 7) A number of cellular nucleotides present within the endoplasmic reticulum regulate UGT function. Further these substances bind to a common allosteric site on UGT to reduce catalytic function.These results suggest that there are functional interaction between P450 and UGT. In addition, endogenous modulators may also important for UGT. Further study is necessary to clarify the impact of interaction between CYP3A4 and UGT2B7 on UGT2B7-catalyzed reaction in vivo.