ISBN 9783843957670

978-3-8439-5767-0, Reihe Organische Chemie

Gabrielle Leveau
Increasing the Yield of Enzyme-Free Copying of RNA

191 Seiten, Dissertation Universität Stuttgart (2025), Softcover, A5

Zusammenfassung / Abstract

The origin of living systems is a question that scientists have been trying to solve for more than 50 years. One promising path follows the RNA World hypothesis, positing that RNA was storing genetic information and could catalyze its own replication before cells existed. Presumably, life could have evolved from a prebiotic system, forming nucleotides, amino acids, (organo)catalysts, and then RNA oligomers. The short RNA strands would then undergo hybridization and ligation, so that copying processes could occur. Enzyme-free primer extension and ligation would be a plausible path to RNA copying, but many challenges remained at the outset of project of the current thesis.

The current project was targeted to investigating enzyme-free copying of RNA using monomers and short oligonucleotides, like dimers and trimers, as building blocks. This form of RNA copying relies on molecular recognition between an RNA strand to be copied, called template, and the short oligonucleotides by Watson-Crick base-pairing and hydrophobic effects. A short RNA strand to be elongated called primer is hybridized to the template, and its 3'-terminus undergoes a nucleophilic attack on the activated phosphate at the 5'-position of a di- or trinucleotide, then leading to the formation of a phosphodiester bond.

The focus of this work was on optimizing the yields of enzyme-free copying of RNA with dinucleotides and trinucleotides using in situ activation. First, the rate constants of more than ten reactions occurring when adenosine 5'-monophosphate (AMP) is activated with 1-ethyl-3-(3-dimethylamino-propyl)carbodiimide (EDC) and 1-ethylimidazole (1-EtIm) as organocatalyst were determined in a model system monitored by nuclear magnetic resonance (NMR). This set of experiments showed how the activated AMP is formed and remains available long enough for extension reactions to occur, despite hydrolysis and other side reactions competing with copying.