Mechanisms of Atypical Drug Kinetics and Interactions

非典型药物动力学和相互作用的机制

• 批准号: 7061796
• 负责人: TIMOTHY S. TRACY
• 金额: $ 23.81万
• 依托单位: UNIVERSITY OF MINNESOTA
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-07-01 至 2009-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7061796
• 关键词: active sites; chemical models; clinical research; computer simulation; conformation; cytochrome P450; drug design /synthesis /production; drug interactions; drug metabolism; enzyme activity; enzyme mechanism; enzyme structure; enzyme substrate complex; heme; isozymes; mathematical model; model design /development; nuclear magnetic resonance spectroscopy; pharmacogenetics; pharmacokinetics; protein structure function; site directed mutagenesis

DESCRIPTION (PROVIDED BY APPLICANT): Atypical kinetic profiles observed with drug metabolizing enzymes, such as the cytochromes P450, can confound in vitro determinations of kinetic parameter estimates. During the development of new drug entities, inaccurate kinetic parameter estimates can lead to incorrect decisions as to the potential success of the drug compound. The long term goals of this research are to understand the biochemical mechanisms resulting in atypical kinetic profiles and develop computer models capable of predicting the occurrence of atypical kinetics. It is generally accepted that two (or more) substrate molecules can bind within the active site of cytochrome P450 enzymes and this phenomenon plays a role in atypical kinetics. NMR work from our laboratory has demonstrated two molecules present in the active site and the presence of an effector causes movement of the primary substrate closer to the heme. Increases in P450 reaction efficiency and reductions in reaction cycle uncoupling also have been observed during CYP2C9 heteroactivation, but preliminary data suggest that not all activator compounds act by the same mechanism. The structure-activity basis for these differential effects is unknown. More recently, we have observed that genetic variants of CYP2C9 exhibit greater degrees of heteroactivation than wild-type enzyme, suggesting that enzyme conformation may also be a factor in the observation of atypical kinetics. The current competing renewal builds upon the above findings and seeks to ascertain; a) the mechanism(s) by which effector molecules alter P450 reaction cycle efficiency and the structure-activity relationships of molecules causing these effects, b) the changes in substrate-heme iron distances and substrate orientation produced by different effectors, and c) how enzyme amino acid alterations affect substrate/effector-protein interactions and thus, activation. From these data, computer models will be developed to predict the occurrence of atypical kinetics and potential drug interactions to assist in the drug development process.

描述（由申请人提供）：用药物代谢酶（例如细胞色素 P450）观察到的非典型动力学曲线可能会混淆动力学参数估计的体外测定。在新药物实体的开发过程中，不准确的动力学参数估计可能会导致对药物化合物的潜在成功做出错误的决定。这项研究的长期目标是了解导致非典型动力学特征的生化机制，并开发能够预测非典型动力学发生的计算机模型。人们普遍认为两个（或更多）底物分子可以在细胞色素 P450 酶的活性位点内结合，这种现象在非典型动力学中发挥作用。我们实验室的核磁共振工作表明，活性位点中存在两个分子，效应子的存在会导致主要底物移动到更靠近血红素的位置。在 CYP2C9 异质激活过程中也观察到 P450 反应效率的增加和反应循环解偶联的减少，但初步数据表明并非所有激活剂化合物都通过相同的机制起作用。这些差异效应的结构-活性基础尚不清楚。最近，我们观察到 CYP2C9 的遗传变异体表现出比野生型酶更大程度的异源激活，这表明酶构象也可能是观察非典型动力学的一个因素。当前的竞争性更新建立在上述发现的基础上，并力求确定； a) 效应分子改变 P450 反应循环效率的机制以及引起这些效应的分子的结构-活性关系，b) 不同效应分子产生的底物-血红素铁距离和底物方向的变化，以及 c) 如何酶氨基酸的改变影响底物/效应子-蛋白质相互作用，从而影响激活。根据这些数据，将开发计算机模型来预测非典型动力学的发生和潜在的药物相互作用，以协助药物开发过程。