Logo image
Back
Quantification of redox thermodynamics shifts within coacervates
Journal article   Open access   Peer reviewed

Quantification of redox thermodynamics shifts within coacervates

Gala Rodriguez, Nicholas B. Watkins, Xagros Faraji, Elizabeth Lee and Lior Sepunaru
Proceedings of the National Academy of Sciences - PNAS, v 122(46), pe2521526122
18 Nov 2025
DOI: https://doi.org/10.1073/pnas.2521526122
PMID: 41237205
Featured in Collection :   UN Sustainable Development Goals @ Drexel
url
https://doi.org/10.1073/pnas.2521526122View
Published, Version of Record (VoR) Open

Abstract

Biophysics and Computational Biology
SignificanceThe earliest enzymes are thought to have formed through the assembly of macromolecules into disordered, secondary phases known as coacervates. While these phases are believed to have played a role in early catalysis, the underlying mechanisms remain poorly understood. Here, we use temperature-dependent electrochemistry to investigate how confinement within coacervates and the resulting increase in local charge concentration affect the reduction of ferricyanide to ferrocyanide. Our results show a decrease in reaction entropy within the coacervate environment, and Raman spectroscopy reveals an inverse relationship in stabilization energy between the reactant and product states. Together, we provide an analytical quantification of changes in reaction thermodynamics within coacervates and offer insights into the chemistry of early life. Coacervates are suggested to be viable protoenzymes due to their propensity to act as catalytic microreactors for biochemical reactions. However, the mechanism by which they alter reaction thermodynamics remains unclear. While extensive research has been conducted displaying the ability of coacervates to compartmentalize a wide variety of reactants, products, and catalysts, insight into how reactant, transition state, and product energies are altered within the droplet continues to be an active area of research. One promising strategy for investigating the thermodynamics and kinetics within the coacervate phase is temperature-dependent electrochemistry, which enables the extraction of reaction entropy, enthalpy, and Gibbs energy. In this work, we use ferri/ferrocyanide, a well-behaved redox couple that has been proposed to be an essential oxidizing agent in prebiotic Earth, to investigate the microenvironment created by the coacervation of poly-L-lysine and polyuridylic acid. We observe an oxidative shift upon partitioning into the coacervates, which temperature-dependent experiments reveal is due to a 40 J/mol K and an 8 kJ/mol increase in reaction entropy and enthalpy, respectively. We attribute the change in entropy to a highly structured water hydrogen-bonding network within the droplets and, subsequently, around the redox probe. Further, we reveal via in situ Raman measurements that the change in reaction enthalpy is due to the destabilization of the product, ferrocyanide, within the ionic coacervate phase.

Metrics

1 Record Views
2 citations in Web of Science

Details

UN Sustainable Development Goals (SDGs)

This publication has contributed to the advancement of the following goals:

#3 Good Health and Well-Being

Source: SDGs in the Output

InCites Highlights

Data related to this publication, from InCites Benchmarking & Analytics tool:

Web of Science research areas
Chemistry, Physical
Logo image