Molecular basis of enzyme-catalyzed pehydrolysis of acetate esters for pretreatment of lignocellulosic biomass

酶催化醋酸酯脱水预处理木质纤维素生物质的分子基础

• 批准号: 0932762
• 负责人: Romas Kazlauskas
• 金额: $ 30万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2013-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0932762&HistoricalAwards=false
• 关键词: Molecular; basis; enzyme; catalyzed; pehydrolysis

0932762KazlauskasSummary Replacing the current biofuels feedstock - corn - with lignocellulosic biomass such as wood, switchgrass or agricultural wastes is a key current goal of bioenergy research. Recalcitrance - inefficient release of sugars from lignocellulosic biomass - is the key problem that must be solved to make this replacement. The proposed solution is an unnatural enzyme-catalyzed reaction to make a strong oxidant peracetic acid. The objective for this application is a molecular-level understanding of an unnatural enzyme-catalyzed reaction - perhydrolysis of esters to form peracetic acid. The central hypothesis is that precise positioning of hydrogen bond donors or acceptors within the active site selectively deactivates water, thus favoring hydrogen peroxide. The PIs have formulated this hypothesis based on the comparison of x-ray crystal structures of enzymes with different abilities to make peracetic acid. The test for this hypothesis will be to correlate the structure and kinetics of perhydrolysis and to design new enzyme variants that make high concentrations of peracetic acid for pretreatment of lignocellulosic biomass. Intellectual Merit: The intellectual merit includes first the molecular-level understanding of how to design enzyme catalyzed non-natural reactions. It will contribute to the research frontier catalytic promiscuity where enzymes catalyze several distinct chemical reactions. Learning how to favor one or another reaction gives insight into the natural process of divergent enzyme evolution and will deepen our understanding of the subtleties of enzymatic catalysis.Broader Impact: The proposed research will generate new fundamental knowledge on the molecular basis of how catalytic activity of enzymes can evolve to new catalytic activities and contribute to the understanding of the mechanisms of oxidation of proteins. The proposed research will contribute to the discovery of efficient routes to peracetic acid to remove lignin to convert lignocellulosic biomass to fuels. The proposed research will educate and train undergraduate students, graduate students and postdoctoral fellows, including students from underrepresented groups in chemical sciences. For the last three years, the PI participates in the Common X-Change program in Saint Paul public schools, which teaches experimental science at the elementary school level. The science teacher partner in this project over the last four years, Ms. Henriette Ngo-Bissoy, an African-American woman, and many of the students in the classes are from underrepresented groups in science. The co-PI, Tschirner, teaches a two week all day summer workshop titled "Topics in Natural Resources: Renewable energy and Bioproducts" for twenty high school teachers. About half of the class is hands-on experiments, inquiry based teaching that is suitable for classroom teaching. The proposed research will also support international cooperation of visitors from Europe and Asia to the PI's laboratories.

0932762Kazlauskas总结用木质纤维素生物质（例如木材、柳枝稷或农业废物）取代当前的生物燃料原料（玉米）是生物能源研究当前的一个关键目标。顽固性——木质纤维素生物质中糖的低效释放——是制造这种替代品必须解决的关键问题。所提出的解决方案是一种非自然酶催化反应，可产生强氧化剂过乙酸。该应用的目的是在分子水平上理解非天然酶催化反应——酯的过水解形成过乙酸。中心假设是，活性位点内氢键供体或受体的精确定位选择性地使水失活，从而有利于过氧化氢。 PI 基于对具有不同制造过乙酸能力的酶的 X 射线晶体结构的比较，提出了这一假设。对这一假设的检验将是关联过水解的结构和动力学，并设计新的酶变体，产生高浓度的过乙酸用于木质纤维素生物质的预处理。智力优点：智力优点首先包括对如何设计酶催化的非自然反应的分子水平理解。 It will contribute to the research frontier catalytic promiscuity where enzymes catalyze several distinct chemical reactions.学习如何促进一种或另一种反应可以深入了解不同酶进化的自然过程，并将加深我们对酶催化的微妙之处的理解。更广泛的影响：这项研究将产生关于酶的催化活性如何进化为新的催化活性的分子基础的新的基础知识，并有助于理解蛋白质氧化的机制。拟议的研究将有助于发现过乙酸的有效途径，以去除木质素，将木质纤维素生物质转化为燃料。拟议的研究将教育和培训本科生、研究生和博士后研究员，包括来自化学科学领域代表性不足群体的学生。在过去的三年里，PI 参加了圣保罗公立学校的 Common X-Change 计划，该计划在小学教授实验科学。过去四年来该项目的科学教师合作伙伴是非裔美国女性 Henriette Ngo-Bissoy 女士，班上的许多学生都来自科学领域代表性不足的群体。联合 PI Tschirner 为 20 名高中教师举办为期两周、全天的夏季研讨会，题为“自然资源主题：可再生能源和生物产品”。大约一半的课程是动手实验、探究式教学，适合课堂教学。拟议的研究还将支持来自欧洲和亚洲的参观者到 PI 实验室的国际合作。