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

如果地球上的生命是在化学作用导致分子形成，分子又自我组装形成细胞的时候开始的，那么这种生命起源前的化学作用一定是地球上某个地方环境条件的自然延伸。中程紫外线（UVC）是早期地球表面的一个强大的环境因素。今天生命的分子基石的遗留光性质是由UVC通量和UVC光化学形成的吗？我们怎么证明呢？PI将首次能够明确地回答生命起源领域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自我修复机制的数据库，将对从基础生物物理学到转化医学的更广泛的科学家群体具有无价之宝。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领域接受技术和科学应用方面的培训。私家侦探将把我们的调查结果传达给公众。在早期地球或其他行星上，生命起源前的化学反应是如何导致生命出现的，这个问题仍然悬而未决。在这个项目中，PI将专注于解决RNA的非酶自我复制机制。这是从益生元合成化学过渡到基于RNA的生命表面起源的进化原始细胞的自组装的决定性步骤。PI将购买中红外飞秒瞬态吸收分光光度计，辅之以FTIR光谱仪，以表征瞬态测量前后固定的样品。红外分光光度计将集成到PI的操作紫外-可见飞秒泵浦探测系统中，激发范围可调，从190nm开始。目前的UV-VIS系统已经允许PI研究一些单体的光动力学（例如，核苷酸），它们的合成途径的选择性，以及相关的光氧化还原循环。然而，低聚化的重要步骤和许多前体，如RNA自我复制中的咪唑桥，只有在红外光谱中才有可行的光谱特征。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.