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Proton Sharing in Polycarboxylic Acids in Aqueous Solution

Tomaník, Lukáš ; Tůma, Jiří ; Öhrwall, Gunnar LU orcid ; Golnak, Ronny ; Le Nguyen, Ngoc Lan ; Credidio, Bruno ; Kaur, Harmanjot ; Slavíček, Petr ; Winter, Bernd and Schewe, H. Christian (2026) In JACS Au 6(6). p.3349-3355
Abstract

We investigate proton sharing in biologically relevant polycarboxylic acids in aqueous solutions using liquid-jet X-ray photoelectron spectroscopy. In contrast to techniques that record time-averaged proton positions, like nuclear magnetic resonance, photoelectron spectroscopy captures instantaneous proton distribution due to its ultrafast probing time scale. The method is, therefore, uniquely sensitive to the occurrence of proton sharing in an aqueous environment, as demonstrated here. We only observe significant proton sharing dynamics in maleic acid, where its monoanionic form shows a single, delocalized peak in the carbon 1s spectrum. Conversely, succinic acid, fumaric acid, malic acid, glutaric acid, and citric acid exhibit... (More)

We investigate proton sharing in biologically relevant polycarboxylic acids in aqueous solutions using liquid-jet X-ray photoelectron spectroscopy. In contrast to techniques that record time-averaged proton positions, like nuclear magnetic resonance, photoelectron spectroscopy captures instantaneous proton distribution due to its ultrafast probing time scale. The method is, therefore, uniquely sensitive to the occurrence of proton sharing in an aqueous environment, as demonstrated here. We only observe significant proton sharing dynamics in maleic acid, where its monoanionic form shows a single, delocalized peak in the carbon 1s spectrum. Conversely, succinic acid, fumaric acid, malic acid, glutaric acid, and citric acid exhibit distinct peaks corresponding to separate, localized COOH and COO– groups, instead of shared protons. Our results reveal that intramolecular proton sharing in water is rather an exception for most biologically relevant polycarboxylic acids. This highlights the importance of enzyme-driven structural changes of polycarboxylic acids associated with proton sharing during metabolic processes.

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author
; ; ; ; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Biomolecules, Carboxylic Acids, Citric Acid (Krebs) Cycle, Photoelectron Spectroscopy, Proton Sharing
in
JACS Au
volume
6
issue
6
pages
7 pages
publisher
The American Chemical Society (ACS)
external identifiers
  • pmid:42358690
  • scopus:105042425383
ISSN
2691-3704
DOI
10.1021/jacsau.6c00377
language
English
LU publication?
yes
id
f9401254-2ce5-4796-954e-65171da402ed
date added to LUP
2026-06-29 15:19:48
date last changed
2026-07-28 23:49:26
@article{f9401254-2ce5-4796-954e-65171da402ed,
  abstract     = {{<p>We investigate proton sharing in biologically relevant polycarboxylic acids in aqueous solutions using liquid-jet X-ray photoelectron spectroscopy. In contrast to techniques that record time-averaged proton positions, like nuclear magnetic resonance, photoelectron spectroscopy captures instantaneous proton distribution due to its ultrafast probing time scale. The method is, therefore, uniquely sensitive to the occurrence of proton sharing in an aqueous environment, as demonstrated here. We only observe significant proton sharing dynamics in maleic acid, where its monoanionic form shows a single, delocalized peak in the carbon 1s spectrum. Conversely, succinic acid, fumaric acid, malic acid, glutaric acid, and citric acid exhibit distinct peaks corresponding to separate, localized COOH and COO<sup>–</sup> groups, instead of shared protons. Our results reveal that intramolecular proton sharing in water is rather an exception for most biologically relevant polycarboxylic acids. This highlights the importance of enzyme-driven structural changes of polycarboxylic acids associated with proton sharing during metabolic processes.</p>}},
  author       = {{Tomaník, Lukáš and Tůma, Jiří and Öhrwall, Gunnar and Golnak, Ronny and Le Nguyen, Ngoc Lan and Credidio, Bruno and Kaur, Harmanjot and Slavíček, Petr and Winter, Bernd and Schewe, H. Christian}},
  issn         = {{2691-3704}},
  keywords     = {{Biomolecules; Carboxylic Acids; Citric Acid (Krebs) Cycle; Photoelectron Spectroscopy; Proton Sharing}},
  language     = {{eng}},
  number       = {{6}},
  pages        = {{3349--3355}},
  publisher    = {{The American Chemical Society (ACS)}},
  series       = {{JACS Au}},
  title        = {{Proton Sharing in Polycarboxylic Acids in Aqueous Solution}},
  url          = {{http://dx.doi.org/10.1021/jacsau.6c00377}},
  doi          = {{10.1021/jacsau.6c00377}},
  volume       = {{6}},
  year         = {{2026}},
}