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

如果地球上的生命起源于化学导致分子构建块，分子构建块又自我组装形成细胞，那么这种生命前的化学反应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如此强大的环境因素。今天生命的分子组成部分的遗留光特性是由UVC通量和UVC光化学形成的吗？我们怎么证明？PI将首次能够明确回答生命起源领域长期存在的中心问题，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受众产生宝贵的价值。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将把我们的发现传达给公众。关于早期地球或其他行星上的生命前化学是如何导致生命出现的问题仍然是一个悬而未决的问题。在这个项目中，PI将专注于解决RNA的非酶自我复制机制。这是从生物合成化学到进化中的原始细胞自组装的过渡中的决定性步骤，用于基于RNA的生命场景的表面起源。PI将购买中红外飞秒瞬态吸收分光光度计，辅以FTIR光谱仪，以表征瞬态测量前后的静止样品。IR分光光度计将被集成到PI的操作UV-VIS飞秒泵浦探测系统中，其具有从190 nm开始的可调激发范围。目前的UV-VIS系统允许PI研究一些单体的光动力学（例如，核苷酸），其合成途径的选择性，以及相关的光氧化还原循环。然而，寡聚化的重要步骤和许多前体，如RNA自我复制中的咪唑鎓桥，仅在IR中具有可行的光谱特征。该奖项反映了NSF的法定使命，并被认为值得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来支持。

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.