基因编码氮杂卡宾类非天然氨基酸模拟二氧化碳氢化酶

项目名称： 基因编码氮杂卡宾类非天然氨基酸模拟二氧化碳氢化酶

项目编号： No.21503268

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 环境科学、安全科学

项目作者： 韩明杰

作者单位： 中国科学院天津工业生物技术研究所

项目金额： 21万元

中文摘要： 为了解决目前严重的环境问题，氢气作为一种清洁的替代能源具有重要意义，但是，安全高效的储存氢气仍是重要挑战。甲酸作为氢气的重要载体，已经引起国际上的普遍重视。二氧化碳氢化酶(CDH)是钼/铁依赖的金属酶，在微生物中广泛存在，它能够催化二氧化碳和氢气的可逆反应生成甲酸。但是，CDH的Molybdopterin辅因子合成困难，使得CDH难以大量表达。Molybdopterin与酶以非共价键形式结合，在苛刻的反应条件下容易解离，限制了CDH的应用。.我们将合成多种含氮杂卡宾的非天然氨基酸， 通过基因密码子扩展方法将其共价连接到蛋白质。氮杂卡宾能够在生物兼容的条件下和多种金属形成复合物，并被氢气还原为金属氢化物。 由此途径，我们将金属氢化物引入到二氧化碳结合蛋白的特定位点，实现二氧化碳的氢气还原。我们的模拟酶相比CDH的主要优势是易于大量表达、耐高温酸碱，有望在替代能源方面获得重要应用。

中文关键词： 二氧化碳还原；二氧化碳氢化酶；氮杂卡宾；金属酶；替代能源

英文摘要： Hydrogen is of great importance as a clean alternative energy to solve environmental problems.However, safe and efficient hydrogen storage is still a great challenge. As an important carrier of hydrogen, formic acid has brought attention world-wide.Carbon dioxide hydrogenase (CDH)is a molybdenum/iron dependent metalloenzyme, which is found in various microbes.The enzyme catalyzes the reversible reaction from carbon dioxide and hydrogen to formate. It is an ideal catalyst for using formate as hydrogen storager. However, the biosynthesis of molybdopterin(cofactor of CDH) is time and energy consuming, limiting the yield of CDH. Molybdopterin is non-covalently attached to the CDH, which is easily to disintegrate under harsh reaction conditions and repetitive turnovers. All these factors limit the application of CDH in hydrogen storage..We will synthesize several unnatural amino acids containing N-heterocyclic carbene, and incorporate them into protein through genetic codon expansion. Our preliminary study found that in biocompatible conditions, N-heterocyclic carbene and various metals could form coordination complexes, which can be reduced to metal hydride by hydrogen.We will further incorporate metal hydride into a specific site of carbon dioxide-binding protein to achieve the reduction of carbon dioxide by hydrogen, similar to the reaction by CDH. Our model enzyme can be easy prepared in large quantity and is resistant to high temperature, acid, and alkali, making it a superior catalyst compared to CDH. The model enzyme has great potential in alternative energy applications

英文关键词： carbon dioxide reduction;carbon dioxide hydrogenase;N-hetercyclic carbene;metalloenzyme;alternative energy