Polyelectrolyte Solutes, Gels, and Coacervates Differentially Impact Proto-Metabolic Ni-Catalyzed Bicarbonate Reduction.
Abstract
Reactions using metal and mineral catalysis likely provided vital organic feedstocks for the process of life’s origination, accessing early metabolic pathways, building proto-metabolism, and providing avenues for compartmentalization. Towards proto-cellular encapsulation, a growing pool of multiply-charged solutes and polymers, as well as organic-rich phases, would have influenced the operation of Earth’s proto-metabolic pathways. Here, we employ quantitative NMR and model molecules containing relevant carboxylate, amine, and phosphate moieties to describe their effect on the catalytic reduction of bicarbonate to formate, the first step in ancient carbon fixation, such as via a precursor reductive Acetyl-CoA (Wood-Ljungdahl) pathway or reductive tricarboxylic acid (TCA) cycle. We find that this proto-metabolic carbon fixation process is relatively robust to build-up of organics, maintaining yields within about twofold despite relatively high concentrations of organic additives. Solute effects are not simply predicted by charge or solute size but depend on adsorption, participation in competing reactions, and solute-solute interactions. Combinations of solutes have a nonadditive effect, with certain pairs resulting in unchanged, intermediate, or increased formate yields compared to either solute alone; for example, sequestration of a yield-suppressing co-solute, adenosine monophosphate (AMP), partially alleviates yield suppression.
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BibTeX
@misc{mullikin2026polyelectrolyte,
title = {{Polyelectrolyte Solutes, Gels, and Coacervates Differentially Impact Proto-Metabolic Ni-Catalyzed Bicarbonate Reduction.}},
author = {Ella Mullikin and Christopher H. House and Christine D. Keating},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv.15008531/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008531/v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Polyelectrolyte Solutes, Gels, and Coacervates Differentially Impact Proto-Metabolic Ni-Catalyzed Bicarbonate Reduction.
AU - Ella Mullikin
AU - Christopher H. House
AU - Christine D. Keating
PY - 2026
DA - 2026/09/09
PB - ChemRxiv
DO - 10.26434/chemrxiv.15008531/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008531/v1
AB - Reactions using metal and mineral catalysis likely provided vital organic feedstocks for the process of life’s origination, accessing early metabolic pathways, building proto-metabolism, and providing avenues for compartmentalization. Towards proto-cellular encapsulation, a growing pool of multiply-charged solutes and polymers, as well as organic-rich phases, would have influenced the operation of Earth’s proto-metabolic pathways. Here, we employ quantitative NMR and model molecules containing relevant carboxylate, amine, and phosphate moieties to describe their effect on the catalytic reduction of bicarbonate to formate, the first step in ancient carbon fixation, such as via a precursor reductive Acetyl-CoA (Wood-Ljungdahl) pathway or reductive tricarboxylic acid (TCA) cycle. We find that this proto-metabolic carbon fixation process is relatively robust to build-up of organics, maintaining yields within about twofold despite relatively high concentrations of organic additives. Solute effects are not simply predicted by charge or solute size but depend on adsorption, participation in competing reactions, and solute-solute interactions. Combinations of solutes have a nonadditive effect, with certain pairs resulting in unchanged, intermediate, or increased formate yields compared to either solute alone; for example, sequestration of a yield-suppressing co-solute, adenosine monophosphate (AMP), partially alleviates yield suppression.
ER -