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

对药物代谢酶的翻译后调控进行了研究。以下是该项目的成果。1)CYP1A2和CYP2C9具有修饰UGT2B7功能的能力。然而，这些P450调节UGT2B7功能的机制(S)似乎不同于CYP3A4。2)通过免疫沉淀法、重叠实验和交联剂1-乙基-3-[3-(二甲氨基)丙基]碳二亚胺(EDC)的交联，证明了更详细的CYP3A4-UGT2B7结合。3)确定了在与UGT2B7相互作用中起作用的CYP3A4候选区域。4)酮康唑对吗啡UGT的抑制作用是通过竞争性抑制和非竞争性抑制两种新机制实现的。5)P450-UGT在大鼠中也存在相关性。有人认为这种相互作用在不同物种之间是保守的。6)酰基-COAS是UGT的内源性激活剂。7)内质网中存在许多细胞核苷酸调节UGT功能。此外，这些物质结合到UGT上的一个共同变构位置上，从而降低了催化功能。这些结果表明，P450和UGT之间存在功能上的相互作用。此外，内源性调节剂对UGT可能也很重要。在体内，CYP3A4和UGT2B7之间的相互作用对UGT2B7催化的反应的影响还有待进一步研究。

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.