EAGER: Defining the Role of UV light in Prebiotic Chemical Evolution: the Imidazolium Bridge in Non-enzymatic RNA Replication

如果生命是在地球上开始的，当时化学物质导致了分子构件，分子构件反过来自组装形成细胞，那么这种生前化学一定是地球上某个地方环境条件的自然延伸。中程紫外光(UVC)是早期地球表面这样一个强有力的环境因素。今天生活的分子构件的遗留光特性是由UVC助熔剂和UVC光化学塑造的吗？我们怎么证明这一点呢？PI将第一次能够明确回答生命起源领域中一个长期存在的核心问题，即紫外线的作用。PI的实验数据库--特别是阐明RNA和DNA自我修复的机制--对于从基础生物物理学到转化医学的更广泛的科学家受众来说将是无价的。学生和博士后研究人员，包括STEM中代表性不足的群体的成员，将在化学、物理和行星科学的交叉点接受技术和科学应用方面的培训。PI将向公众传达我们的发现。早期地球或其他行星体上的益生化学是如何导致生命出现的问题仍然悬而未决。在这个项目中，PI将专注于解决RNA的非酶自我复制的机制。这是从益生菌合成化学向基于RNA的生命场景表面起源的进化的原始细胞自组装过渡的决定性步骤。PI将购买中红外飞秒瞬变吸收光谱仪，并辅之以FTIR光谱仪，以表征瞬变测量前后静止的样品。红外分光计将被集成到PI的可操作的UV-VIS飞秒泵浦-探测系统中，激发范围从190 nm开始可调。目前的UV-Vis系统已经允许PI研究一些单体(例如核苷酸)的光动力学，它们合成路径的选择性，以及相关的光氧化还原循环。然而，齐聚的重要步骤以及许多前体，如RNA自我复制中的咪唑桥，只有在IR中才有可行的光谱特征。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

If life began on Earth when chemistry led to the molecular building blocks, which in turn self-assembled to form cells, then this prebiotic chemistry must have been a natural extension of the environmental conditions somewhere on the planet. Mid-range UV light (UVC) was one such robust environmental factor on the surface of early Earth. Were the legacy photoproperties of the molecular building blocks of today's life shaped by UVC fluxes and UVC photochemistry? How could we prove that? The PI will be able for the first time to answer unambiguously a long-standing central question in the origins of life field, regarding the role of UV light. The PI's experimental database - in particular, elucidating the mechanisms of RNA and DNA self-repair, will be invaluable to a much broader audience of scientists from basic biophysics to translational medicine. Students and postdoctoral researchers, including members of underrepresented groups in STEM, will receive training in technology and scientific applications at the intersection of chemistry, physics, and planetary science. The PI will communicate our findings to the general public.The question of how prebiotic chemistry, on early Earth or other planetary bodies, led to the emergence of life remains wide open. In this project the PI will focus on resolving the mechanisms for non-enzymatic self-replication of RNA. This is the defining step in the transition from prebiotic synthetic chemistry to the self-assembly of evolving protocells for surficial origins of life scenarios based on RNA. The PI will purchase mid-infrared femtosecond transient absorption spectrophotometer, complemented by an FTIR spectrometer to characterize samples stationary before and after transient measurements. The IR spectrophotometer will be integrated into the PI's operational UV-VIS femtosecond pump-probe system with a tunable excitation range starting at 190 nm. The current UV-VIS system has allowed the PI to study the photodynamics of some monomers (e.g., nucleotides), the selectivity of their synthetic pathways, and related photoredox cycles. However, the important steps of oligomerization, and many of the precursors, like the imidazolium bridge in RNA self- replication, have viable spectroscopic signatures only in the IR.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.