Metallopeptide Based Mimics of Mononuclear Nonheme Iron Enzymes: Understanding Enzymatic Reactivity Using Designed Metallopeptides

基于金属肽的单核非血红素铁酶模拟物：使用设计的金属肽了解酶反应性

基本信息

批准号：
10797337
负责人：
Jason M Shearer
金额：
$ 9.59万
依托单位：
TRINITY UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2021
资助国家：
美国
起止时间：
2021-04-01 至 2025-03-31
项目状态：
未结题

项目摘要

Project Abstract. Mononuclear nonheme iron (mnhFe) enzymes perform an array of chemically diverse reactions that are vital to many different aspects of human health including: antibiotic biosynthesis, production of key metabolites, and DNA repair. Thus, the misregulation and dysfunction of mnhFe enzymes have been implicated in a number of disorders including neurodegeneration, cancers, diabetes, and cardiovascular diseases. A large class of mnhFe enzymes contains a reduced Fe(II) ion that activates dioxygen, forming a highly reactive FeIII-O2– species. Once formed, this FeIII-O2– intermediate can promote a large number of different reactions leading to an enormous diversity in chemical reactivity. Despite the surprising similarities in active-site (and sometimes substrate) structures, each enzyme promotes a highly specific reaction and yields a highly specific product. The factors leading to such high reaction specificity from these similar active-site structures are not fully understood. The overarching goal of the work proposed herein is to understand how the FeIII-O2– intermediate in two mnhFe enzymes, cysteine dioxygenase (CDO) and isopenicillin-N-synthase (IPNS), can selectively promote two vastly different reactions on structurally similar substrates: sulfur oxygenation (CDO) vs C-H atom abstraction (IPNS). Both CDO and IPNS modify a thiol-containing substrate once it is coordinated to the iron-center. We hypothesize that the differential reactivity in these two enzymes is promoted by the orientation of the nominal S(3p)-type orbital of the coordinated substrate, which will turn on or off a thermodynamically favored S-based oxygenation reaction. To explore this hypothesis, we will prepare a library of structurally related metallopeptides that will promote either CDO- or IPNS-like chemistries. The major difference between these peptides will be the orientation of the S(3p)-type orbital relative to the vector of attack of the superoxo ligand of the FeIII-O2– intermediate. Because the geometric and electronic structures of these peptides will all be nearly identical, all differences in reactivity will be attributable to the S(3p) orbital orientation. This research makes use of a large number of tools encountered in bioinorganic chemistry, thus providing an excellent training platform for undergraduate researchers. In addition to biomimietic metallopeptide design and synthesis, these systems will be subjected to mechanistic, spectroscopic (electronic absorption, EPR, (M)CD, X-ray absorption, vibrational and Mössbauer spectroscopies), and high-level computational studies. The use of metalloenzyme mimics in our investigations is especially noteworthy; few studies have been performed where insight into specific biochemical processes are revealed through metallopeptide based metalloenzyme mimics. Therefore, completion of this project will not only reveal interesting aspects of mnhFe biochemistry, but will also expand the limits of investigations concerning metallopeptide based metalloenzyme mimics.

项目摘要。单核非血红素铁（MNHFE）酶进行一系列化学潜水员对人类健康许多不同方面至关重要的反应，包括：抗生素生物合成，生产关键代谢产物和DNA修复。那是MNHFE酶的错误和功能障碍在许多疾病中实施，包括神经变性，癌症，糖尿病和心血管疾病。一大类MNHFE酶含有降低的Fe（II）离子，该离子激活二恶英，形成高度反应性feiii-o2种。一旦形成，这个Feiii-O2 - 中级可以促进大量不同的不同反应导致化学反应性巨大多样性。尽管有效站点有令人惊讶的相似性（有时是底物）结构，每种酶都会促进高度特异性的反应并产生高度的反应特定产品。从这些相似的活跃位点结构中导致如此高反应特异性的因素是不完全理解。本文提出的工作的总体目标是了解FEIIII-O2 –如何在两种MNHFE酶，半胱氨酸二氧酶（CDO）和异跨霉素-N-N-Synthase（IPNS）中的中间体，可以在结构相似的底物上有选择地促进两个截然不同的反应：硫氧合（CDO）与 C-H原子抽象（IPN）。 CDO和IPN将含硫醇的底物与铁中心协调后，都会修改含硫醇的底物。我们假设标称S（3p）型的方向促进了这两种酶的差异反应性协调的底物的轨道，将打开或关闭热力学偏爱的基于S的氧合反应。为了探讨这一假设，我们将准备一个结构相关的金属肽库促进类似CDO或IPNS的化学。这些宠物之间的主要区别将是 S（3p）型轨道相对于FeIIII-O2 –超氧配体的攻击者的方向中间的。因为这些宠物的几何和电子结构几乎都是相同的反应性差异将归因于S（3p）轨道取向。这项研究利用了生物无机化学中遇到的大量工具，从而提供了本科研究人员的出色培训平台。除了植物金属肽设计和合成，这些系统将经过机械，光谱（电子滥用，EPR，（M）CD， X射线抽象，振动和Mössbauer光谱法和高级计算研究。使用金属酶模仿我们的调查特别值得注意。很少有研究在通过基于金属肽的金属酶模拟物揭示了对特定生化过程的洞察力。因此，该项目的完成不仅会揭示MNHFE生物化学的有趣方面，而且还将扩大有关基于金属肽的金属酶模拟的投资限制。