Biophysical Society Conference | Tahoe 2023

Proton Reactions: From Basic Science to Biomedical Applications

Wednesday Speaker Abstracts

EXPLORING PROTONATION REACTIONS AND STABILITY OF INTACT CARBONIC ACID IN ALCOHOL SOLVENT MIXTURES Valeriia Baranauskaite 1 ; Daniel Aminov 1 ; Dina Pines 1 ; Ehud Pines 1 ; 1 Ben Gurion University of the Negev, Chemistry, Beer Sheva, Israel Carbonic acid (CA) is an important compound found in various natural systems, but its fast decomposition into H 2 O and CO 2 has hindered its study. Researchers have struggled to isolate and characterize CA due to its instability in the presence of water and acids. However, recent advances in experimental techniques have provided new opportunities for investigating this elusive molecule. These studies have shown that water and protons serve as primary catalysts for the decomposition of CA. In light of these observations, it is reasonable to suggest that CA may exhibit increased stability when present in non-aqueous media. In this study, we employed an advanced stopped-flow setup to investigate the kinetics of intact CA in ethanol solutions. Our findings indicate that CA is more stable in ethanol than in water, which opens up new avenues for studying this compound. We studied two different processes - dissociation to water and CO 2 and proton transfer from carbonic acid to a base - and determined the pKa of CA as a function of temperature, as well as the lifetime of CA in ethanol solutions and in mixtures with several aprotic solvents. We successfully modeled the protonation reaction of Brønsted bases by CA in ethanol, demonstrating that efficient protonation of mild bases was driven by the increased stability of CA in ethanol. Our study offers promising prospects for further investigations of intact CA in non-aqueous media. By identifying experimental conditions that promote long-lived CA in solutions, we can study its spectroscopic properties and chemistry using steady-state techniques. We suggest that long-lived intact CA may be found in hydrophobic biological environments and that the reactivity of intact CA in biological systems should not be overlooked.

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