Genetically Controlled Syntheses of New Polymeric Materials

9510031 Tirrell这个项目将开发制备结构明确的人工蛋白质的方法，这些蛋白质带有反应性的烯基、二烯基、乙炔和吡咯基官能团。该项目的一个关键方面是使用人工基因来指导统一聚合物链的合成，这些均一聚合物链将直接(通过加入非天然氨基酸)或间接(通过翻译后修饰反应)获得反应性功能。在任何一种方法中，都将利用细菌蛋白质合成的保真度来生产聚合物材料，其特征是精确控制链长、序列和立体化学。直接方法将探索与异亮氨酸、苯丙氨酸、组氨酸或酪氨酸相关的六种人工氨基酸(及其几种变体)的翻译活性。越来越多的证据表明，细菌蛋白质合成机制可以利用比通常由信使RNA模板编码的20种氨基酸更广泛的氨基酸。由于两个事实，为本研究选择的氨基酸类似物特别令人感兴趣：i)。没有一种天然氨基酸带有烯基、二烯基、乙酰基或吡咯基，以及ii)。这样的官能团可以用来赋予聚合物材料有趣的和潜在有用的化学和电化学性质。用于直接成立公司的办法包括：i)。合成编码感兴趣序列的人造基因，其中天然类似物编码代替目标非天然氨基酸，ii)。在适当的营养缺陷型细菌菌株中克隆人工基因，以及iii)。在含有非天然氨基酸(通常缺乏天然类似物)的介质中诱导目标蛋白质合成。这一策略已经被成功地用于几种非天然氨基酸，包括硒蛋氨酸、对氟苯丙氨酸、3-硫代丙氨酸、三氟亮氨酸、氮杂二羧酸、脱氢脯氨酸和硫代脯氨酸。还将探讨涉及翻译后修改的补充战略。在这种方法中，蛋白质生物合成将被用来制备适当设计的“基础聚合物”，这些聚合物将用带有烯基、二烯基、乙炔或吡咯基的试剂进行修饰。无论采用哪种方法制备的聚合物都要经过仔细的分子结构、超分子组织和功能性质的分析。将特别关注产生含有吡咯基侧链的电化学可切换蛋白质膜的前景。这种薄膜将作为传感器、执行器和受控输送装置的组件具有潜在的实际用途。本研究旨在利用人工基因合成具有高度可控结构的氨基酸聚合物。所选择的聚合物在自然界中不存在，并且将被设计成具有有趣的电学和其他性能。***

9510031 Tirrell This project will develop methods for the preparation of architecturally well-defined artificial proteins carrying reactive olefinic, dienyl, acetylenic and pyrrolyl functional groups. A key aspect of the project is the use of artificial genes to direct the synthesis of uniform polymer chains, which will acquire reactive functionality either directly (through the incorporation of unnatural amino acids), or indirectly (through post-translational modification reactions). In either approach, the fidelity of bacterial protein synthesis will be exploited to produce polymeric materials characterized by precise control of chain length, sequence, and stereochemistry. The direct approach will explore the translational activity of six artificial amino acids (and several variants thereof) related to isoleucine, phenylalanine, histidine or tyrosine. There is increasing evidence that the bacterial protein synthesis machinery can utilize a braoder range of amino acids than the twenty that are normally encoded by messenger RNA templates. The amino acid analogues chosen for this study are of particular interest owing to two facts: i). none of the natural amino acids carries olefinic, dienyl, acetylenic or pyrrolyl groups, and ii). such functional groups can be used to endow polymeric materials with interesting and potentially useful chemical and electrochemical properties. The approach to be used for direct incorporation involves: i). synthesis of an artificial gene encoding the sequence of interest, with the natural analogue encoded in place of the target unnatural amino acid, ii). cloning of the artificial gene in an appropriate auxotrophic bacterial strain, and iii). induction of target protein synthesis in a medium containing the unnatural amino acid (and generally depleted of the natural analogue). This strategy has been demonstrated successfully with several unnatural amino acids, including selenomethionine, p-fluorophenylalanine, 3- thienylalanine, trifluoroleucine, azetidinecarboxylic acid, dehydroproline, and thiaproline. Complementary strategy involving post-translational modification will also be explored. In this approach, protein biosynthesis will be used to prepare appropriately designed "base polymers," which will be modified with reagents carrying olefinic, dienyl, acetylenic or pyrrolyl groups. Polymers prepared by either route will be subjected to careful analyses of molecular structure, supramolecular organization, and functional properties. Particular attention will be given to the prospects for creating electrochemically switchable protein films containing pyrrolyl side chains. Such films would be of potential practical use as components of sensors, actuators and controlled delivery devices. %%% This research aims to carry out the synthesis of amino acid polymers with highly controlled structures, through the use of artificial genes. The polymers selected do not occur in nature and will be designed to have interesting electrical and other properties. ***