XAS STUDIES OF A CYTOCHROME P450 INTERMEDIATES

细胞色素 P450 中间体的 XAS 研究

基本信息

批准号：
8170249
负责人：
ERIK C WASINGER
金额：
$ 0.13万
依托单位：
STANFORD UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2010
资助国家：
美国
起止时间：
2010-05-01 至 2011-02-28
项目状态：
已结题

项目摘要

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The cytochrome P450 enzymes were first isolated and reported in 1966 and have subsequently been found to be ubiquitous in nature. In Man, there are about 60 P450 enzymes, involved mainly in oxidation reactions. P450s in the liver are broad spectrum oxidants that metabolize drugs, pro- drugs, and xenobiotics, making them the most important enzymes from a pharmacological perspective because they control drug dosing and clearance. Other P450s are intimately involved in disease states such as breast cancer (due to over-production of the P450 enzyme aromatase that makes estradiol), prostate cancer (linked to over-production of P450 CYP17), and liver disease (due to over-production of the inducible P450 CYP2E1). Physical, kinetic and mechanistic studies of P450 oxidants will provide valuable information, but those studies have been precluded by the inability to produce the oxidizing intermediates at high conversion under controlled conditions. P450s are heme-containing enzymes that differ from other heme enzymes in that they have a thiolate (from protein cysteine) as the fifth ligand to iron. They have long been thought to effect oxidation by reaction of an iron(IV)-oxo porphyrin radical cation known as Compound I, which is related to well characterized Compound I derivatives of other heme-containing enzymes such as peroxidases and catalases. The one electron reduced species from Compound I, an iron(IV)-oxo species with a neutral porphyrin, is termed Compound II. Despite the common belief that Compound I is the active oxidant of a P450, these species have not been available from rapid stopped-flow mixing or rapid freeze quench studies that date back to 1968. In fact, the improvements in mixing methods in the past four decades have been marginal, and progress in detecting P450 oxidants has been slow despite dozens of reported unsuccessful or marginally successful attempts and, one assumes, scores of unreported failures. Our group developed a new approach for production of the iron-oxo derivatives of P450 enzyme

该副本是利用众多研究子项目之一由NIH/NCRR资助的中心赠款提供的资源。子弹和调查员（PI）可能已经从其他NIH来源获得了主要资金，因此可以在其他清晰的条目中代表。列出的机构是对于中心，这不一定是调查员的机构。首先分离出细胞色素P450酶，并于1966年进行报道，随后发现本质上无处不在。在人中，大约有60个P450酶，主要参与氧化反应。肝脏中的P450是对药物，促药和异种生物的代谢氧化剂的广泛氧化剂，从药理角度来看，它们是最重要的酶，因为它们控制了药物给药和清除率。其他P450与乳腺癌等疾病状态密切相关（由于P450酶芳香酶的生产过多，使前列腺癌（与P450 CYP17的过度生产有关）和肝病（由于诱导P450 CYP2E1的生产过多，与生产过量有关）。 p450氧化剂的物理，动力学和机械研究将提供有价值的信息，但是这些研究已无法在受控条件下高转化率下在高转化率下产生氧化中间体。 P450是含血红素的酶，与其他血红素酶不同，因为它们具有硫醇酸盐（从蛋白质半胱氨酸）作为第五配体到铁。长期以来，人们一直认为它们通过铁（IV）-Oxo卟啉自由基阳离子的反应作用，称为化合物I，这与表征良好的化合物I衍生物有关其他含血红素的酶（例如过氧化物酶和催化酶）的衍生物。一种电子从化合物I（具有中性卟啉的铁（IV） - 氧化物物种）中的一种电子被称为化合物II。尽管人们普遍认为化合物I是P450的活跃氧化剂，但这些物种尚未从快速停止流量混合或快速冻结研究可追溯到1968年。实际上，在过去的四十年中，混合方法的改善却是微不足道的，并且在发现p450氧化剂的过程中却很慢，尽管p450氧化量很快，但仍有不受影响的速度，并且不受效率地弥补了一致的范围。失败。我们的小组开发了一种新方法来生产P450酶的铁氧衍生物