Elucidating Water-Ionic Liquid-Enzyme Mixtures Interactions for Enhanced Deconstruction of Cellulosic Biomass

PI：Maupin，Christopher Proposal number：1337044机构：科罗拉多矿物学院标题：阐明水-离子液体-酶混合物相互作用加强纤维素生物分解工程增强纤维素分解系统对于经济高效地利用生物质生产液体燃料和其他增值化学品至关重要。不幸的是，结晶纤维素底物的不溶性和多相催化带来的局限性导致了较高的反应时间，不适合大规模的工业过程。任务型离子液体(IL)是一种很有前途的绿色？一种超级溶剂，能够快速溶解结晶纤维素生物质，同时保持纤维素酶活性，从而提供了一条有希望的单步、均相降解纤维素生物质的途径。然而，对于影响酶结构、活性和稳定性的潜在的IL-酶相互作用的了解仍然很多。在这个计算和实验相结合的项目中，我们提出了一个双管齐下的方法来评估三个IL对两个纤维素酶的相互作用。正在研究的纤维素酶在IL-H2O混合物中表现出不同程度的活性，从而能够识别功能所需的特定酶特性，而不同的IL-H2O混合物能够识别有利于影响酶功能的特定IL特性。识别导致酶功能和活性改变的特定IL-酶相互作用将通过以下目标完成：(1)对IL-H2O-酶系统进行分子动力学模拟。这些模拟将揭示特定的IL-酶相互作用及其对酶的动态波动和整体结构的影响。(2)对IL-H2O-酶和IL-H2O-纤维素齐聚物体系进行热力学积分计算。这些计算探索了IL进入纤维素酶活性中心的能力，阐明了竞争溶剂化能的作用。(3)对IL-H2O-酶体系进行了CpHMD模拟。这些模拟将揭示IL混合物对活性中心关键残基的pKa的影响，以及(4)对IL-H2O-酶降解纤维素的动力学分析。这些实验将揭示IL-H2O混合物对观察到的酶活性的影响。计算和实验研究将提供对IL-酶相互作用及其对结构、动态波动、pKa值和溶剂化的影响的更多分子水平的理解，将阐明溶剂环境如何影响酶和其他与工业过程相关的大分子系统的功能。此外，对促进结构稳定性和活性的酶和IL属性的评估将使使用合理的设计来为广泛的行业制造定制的酶和IL成为可能。与研究紧密结合的是对下一代科学家和工程师的多个教育水平的教育。在STEM领域吸引代表性不足的群体是通过与小马丁·路德·金共同开展的针对预科学生的研究经验(REPS)推广计划来完成的。早年，丹佛的一所高中。这项研究工作将通过研究文章、区域和国家会议广泛传播，此外还将纳入美国科学促进会太平洋司区域会议和博伊西州立大学的计算讲习班，博伊西州立大学主要是一所本科院校。

PI: Maupin, ChristopherProposal Number: 1337044Institution: Colorado School of MinesTitle: Elucidating Water-Ionic Liquid-Enzyme Mixtures Interactions for Enhanced Deconstruction of Cellulosic BiomassEngineering enhanced systems for the deconstruction of cellulose is essential to the cost-effective utilization of biomass for production of liquid fuels and other value added chemicals. Unfortunately, the insolubility of the crystalline cellulose substrate and resulting limitations incurred by heterogeneous catalysis leads to high reaction times that are not suitable for large scale industrial processes. Task specific ionic liquids (IL) are a promising ?green? super solvent that enable the rapid dissolution of crystalline cellulosic biomass while also retaining cellulase enzyme activity thereby providing a promising route to a single step, homogeneous phase degradation of cellulosic biomass. However, much remains in regards to understanding the underlying IL-enzyme interactions affecting enzyme structure, activity, and stability.In this combined computational and experimental project we propose a two pronged approach to evaluate the interactions between three ILs on two cellulase enzymes. The cellulase enzymes being studied have shown varying degrees of activity in IL-H2O mixtures, allowing for the identification of specific enzyme features necessary for functionality while the different IL-H2O mixtures enable the identification of specific IL features that favorably affect enzyme functionality. The identification of specific IL-enzyme interactions leading to altered enzyme functionality and activity will be accomplished through the following objectives: (1) MD simulations on IL-H2O-enzyme systems. These simulations will reveal specific IL-enzyme interactions and their impact on dynamic fluctuations and the overall structure of the enzyme, (2) Conduct Thermodynamic Integration calculations on IL-H2O-enzyme and IL-H2O-cellulose oligomer systems. These calculations probe the ability of the IL to enter the active site of cellulose enzymes and illuminate the role of competing solvation energies, (3) Conduct CpHMD simulations on IL-H2O-enzyme systems. These simulations will reveal the impact of IL mixtures on the pKa of critical residues in the active site, and (4) Conduct kinetic analysis of IL-H2O-enzyme degradation of cellulose. These experiments will reveal the impact of IL-H2O mixtures on the observed enzyme activity.The computational and experimental studies will provide an increased molecular-level understanding of the IL-enzyme interactions and the resulting effect on structure, dynamical fluctuations, pKa values, and solvation will elucidate how the solvent environment impacts the functionality of enzymes and other macromolecule systems relevant to industrial processes. In addition, evaluation of the enzyme and IL properties that facilitate structural stability and activity will enable the use of rational design to create tailored enzymes and ILs for a wide range of industries. Closely integrated with the research is the education of the next generation of scientists and engineers across multiple education levels. Engaging underrepresented groups in STEM fields is accomplished through the Research Experience for Pre-Collegiate Students (REPS) outreach program with Martin Luther King Jr. Early ollege, a Denver high school. The research effort will be broadly disseminated through research articles, regional and national meetings, in addition to the incorporation into computational workshops at the regional AAAS Pacific Division meetings and Boise State University, a primarily undergraduate institution.