Enzyme cooperativity, biocatalysis and bioconjugation

酶不仅是令人着迷的催化剂，而且也是大多数药物的靶标。由于酶具有复杂的三维结构，它表现出许多在化学催化剂中很少发现的有趣特征。******细胞色素P450酶（CYPs或P450）是在所有王国中发现的普遍存在的酶，参与各种过程，如药物代谢，天然产物的生物合成，类固醇，脂质等。已知一些p450（如CYP3A4）表现出变构效应和/或使用独特的协同机制，涉及同时与酶结合的相同或不同配体的多个拷贝之间的直接相互作用。使用现有的方法来描述这种行为是相当具有挑战性的。为了研究CYP3A4的变构和协同性，我们开发了一种新的生物偶联方法和一些即将应用的生物物理方法。我们目前也在开发一种使用等温量热法的动力学方法。******在合成化学中使用酶是有利的，不仅因为它与环境友好的条件相容，而且因为许多酶催化的反应是化学催化剂无法达到的。例如，我们对p450感兴趣是因为它们能够在未活化的C-H键上催化选择性羟基化。几丁质酶和木质素分解过氧化物酶也引起了我们的兴趣，因为它们分别可以降解一些最坚硬和最丰富的底物，几丁质和木质素。我们建议开发新的方法来促进生物催化的应用。例如，我们率先使用化学助剂来控制和预测p450催化反应的区域选择性和立体选择性。利用一种具有大混杂底物结合袋的酶，我们最近证明了通过合理诱变限制活性位点可以显著改变酶的选择性。最后，我们收集了初步数据，表明机械化学可以积极影响酶的过程，甚至超越目前的化学工业过程。我们建议将这些方法应用于感兴趣的特定过程并对其进行优化。******这项研究计划的总体目标是开发新的工具来研究酶，并将这些工具应用于酶学和促进生物催化。具有代表性的具体目标包括：******-应用我们的生物物理方法研究氨基糖苷3'-磷酸化转移酶***-在动力学模式下使用等温量热法研究P450 ***-使用我们的新CYP3A4生物偶联物并生成新的CYP3A4生物偶联物来研究CYP3A4变构和协同性***-确定新的化学助剂来控制P450的区域和立体选择性***-应用，优化和研究我们的机械化学方法与新的酶促反应

Enzymes are not only fascinating catalysts, but they are also the target of most drugs. Thanks to their complex 3D structure, enzymes show many interesting characteristics rarely found in chemical catalysts.******Cytochrome P450 enzymes (CYPs or P450s) are ubiquitous enzymes found across all kingdoms and involved in processes as varied as drug metabolism, biosynthesis of natural products, steroids, lipids, and more. Some P450s (e.g. CYP3A4) are known to show allosteric effects and/or use a unique cooperativity mechanism involving direct interactions between multiple copies of the same or different ligands bound to the enzyme at the same time. Such a behavior is quite challenging to delineate using existing methods. In order to study the allostery and cooperativity of CYP3A4, we have developed a new bioconjugation approach and a number of biophysical methods which will be applied. We are also currently developing a kinetic method using isothermal calorimetry.******The use of enzymes in synthetic chemistry is advantageous not only because it is compatible with environmentally benign conditions but also because many enzymes catalyze reactions that are inaccessible to chemical catalysts. For example, P450s are of interest to us because of their ability to catalyze selective hydroxylations at unactivated C-H bonds. Chitinases and lignolytic peroxidases are also of interest to us because they can degrade some of the toughest and most abundant substrates, chitin and lignin respectively. We propose to develop new methods to facilitate biocatalytic applications. For example, we have pioneered the use of chemical auxiliaries to control and predict the regio- and stereo-selectivity of P450-catalyzed reactions. Using an enzyme with a large promiscuous substrate binding pocket, we have recently demonstrated that constraining the active site via rational mutagenesis can dramatically shift the selectivity of the enzyme. Finally, we have gathered preliminary data demonstrating that mechanochemistry can positively affect enzymatic processes and even surpass current chemical industrial processes. We propose to apply and optimize these methods for specific processes of interest.******The overall goals of this research program are to develop new tools to study enzymes and apply these in enzymology and to facilitate biocatalysis. Representative specific aims include:******- Apply our biophysical methods to study aminoglycoside 3'-phosphoryltransferase***- Study P450 using isothemal calorimetry in kinetics mode***- Use our new CYP3A4 bioconjugates and generate new ones to study CYP3A4 allostery and cooperativity***- Identify new chemical auxiliaries to control the regio- and stereo-selectivities of P450s***- Apply, optimize and investigate our mechanochemical method with new enzymatic reactions