PHOTODYNAMICS OF NUCLEOBASES

核碱基的光动力学

• 批准号: 1301305
• 负责人: Mattanjah de Vries
• 金额: $ 51.13万
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-15 至 2018-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1301305&HistoricalAwards=false
• 关键词: PHOTODYNAMICS; NUCLEOBASES

Through this award, funded by the Chemical Structure, Dynamics, and Mechanisms - A Program of the Division of Chemistry, Prof. Mattanjah S. de Vries from the University California Santa Barbara and his team, will measure photochemical properties in clusters of stacked, hydrogen bonded, and microsolvated nucleobases. These studies will constitute a new step in the reductionist approach to understanding nucleobase photodynamics. Gas phase spectroscopy will be compared with quantum computations in collaboration with Dr. Nachtigallová at the Academy of Sciences of the Czech Republic. This approach, so far applied to isolated nucleobases, suggests a general process in which, following absorption of UV light, DNA bases can avoid chemical transformation by very rapidly diffusing the excitation energy to heat (in a process called internal conversion) which can safely be transferred to the environment. This process strongly depends on molecular structure and is remarkably prevalent in the specific forms in which nucleobases occur in biological contexts. However, intermolecular interactions also affect these processes. Compared to single bases, pi-stacking opens new possible excited state decay pathways, involving exciplex states, which will be studied in the picosecond time domain, as a function of precise intermolecular structure. Understanding the precise role of these interactions, which is the objective of this study, is crucial for fully understanding the way light interacts with biological molecules.Understanding the response of DNA bases to ultraviolet (UV) radiation is critical for both practical and fundamental reasons. Nucleobase photochemistry following UV absorption constitutes a fundamental step in radiation-induced DNA damage. It appears that DNA bases are especially stable against damage caused by UV light. This unique property may have played a role in the selection of the building blocks of life four billion year ago. The bases that make up today's DNA may be the molecules that were most suited to survive harsh UV radiation on an early earth. This work will study the details of the molecular properties that make our genetic material so robust against photochemical damage. The work employs techniques of ultrafast laser spectroscopy, mass spectrometry and computational chemistry. In addition to training graduate students in these advanced methods, undergraduate students and high school students will also be exposed to this work as part of a number of outreach programs, including an ongoing collaboration with Jackson State University.

通过这个奖项，由化学结构，动力学和机制-化学系的一个程序，教授Mattanjah S。来自加州大学圣巴巴拉分校的de弗里斯和他的团队将测量堆叠的、氢键合的和微溶剂化的核碱基簇的光化学性质。这些研究将构成一个新的一步，在还原论的方法来理解核碱基光动力学。将与捷克共和国科学院的Nachtigallová博士合作，将气相光谱与量子计算进行比较。这种方法，到目前为止应用于孤立的核碱基，提出了一个一般的过程，其中，在吸收紫外线后，DNA碱基可以通过非常迅速地将激发能扩散到热（在一个称为内部转换的过程中）来避免化学转化，该过程可以安全地转移到环境中。这一过程强烈依赖于分子结构，并且在生物学背景下发生的核碱基的特定形式中非常普遍。然而，分子间相互作用也影响这些过程。与单碱基相比，π-堆积开辟了新的可能的激发态衰减途径，涉及激基复合物状态，这将在皮秒时域中研究，作为精确分子间结构的函数。了解这些相互作用的确切作用，这是本研究的目标，是至关重要的充分了解光与生物分子相互作用的方式。了解DNA碱基对紫外线（UV）辐射的反应是至关重要的，无论是从实际还是从根本上讲。紫外吸收后的碱基光化学反应是辐射诱导DNA损伤的基本步骤。看来DNA碱基对紫外线造成的损伤特别稳定。这种独特的性质可能在40亿年前选择生命的组成部分中发挥了作用。构成今天DNA的碱基可能是最适合在早期地球上经受严酷紫外线辐射的分子。这项工作将研究分子特性的细节，使我们的遗传物质对光化学损伤如此强大。这项工作采用了超快激光光谱学、质谱学和计算化学技术。除了用这些先进的方法培训研究生外，本科生和高中生也将接触这项工作，作为一些推广计划的一部分，包括与杰克逊州立大学正在进行的合作。