<div><div>Protons play a central role in many chemical reactions in living organisms. In some cases, a proton may be shared between two nearby molecular groups rather than being localized on just one. This phenomenon can strongly influence the properties and reactivity of biomolecules and is important for enzyme function.</div></div><div>Researchers led by Hanns Christian Schewe (IOCB Prague and Heyrovský Institute of the CAS) together with Lukáš Tomaník (UCT Prague and Fritz Haber Institute of the Max Planck Society) have now investigated proton sharing in a range of biologically relevant polycarboxylic acids dissolved in water, including several molecules related to the citric acid cycle (Krebs cycle).Using liquid-jet X-ray photoelectron spectroscopy (LJ-PES), a technique that reveals the chemical environment of atoms in molecules dissolved in water, the team was able to probe the position of protons on an ultrafast time scale. Unlike techniques such as NMR, which provide a time-averaged picture, photoelectron spectroscopy captures the instantaneous distribution of protons and can therefore distinguish more directly between localized and shared states.The results showed significant proton sharing only in maleic acid dissolved in water. In contrast, protons remained mostly localized at individual carboxylic groups in succinic acid, fumaric acid, malic acid, glutaric acid and citric acid. This suggests that proton sharing is not a common feature of these molecules when they are freely dissolved in water.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/IOCB_Prague_Cropped_part_of_the_cover_by_Schewe_et_al_with_the_use_of_Nano_Banana_2_0_2_2a408dbeb5.webp" alt="IOCB Prague: Cropped part of the cover by Schewe et al. with the use of Nano Banana 2.0: Full cover by Schewe et al. with the use of Nano Banana 2.0." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_IOCB_Prague_Cropped_part_of_the_cover_by_Schewe_et_al_with_the_use_of_Nano_Banana_2_0_2_2a408dbeb5.webp 117w," sizes="100vw" width="1620" height="2154">The difference appears to be largely controlled by molecular geometry. In maleic acid, the two carboxylic groups are held close together, creating favorable conditions for proton sharing. More flexible molecules can adopt conformations in which the groups are farther apart, while water molecules form strong hydrogen bonds with them and favor localized protons.However, the situation may be different inside proteins. When a carboxylic acid binds in the active site of an enzyme, its shape and position can be tightly constrained. Such an environment could bring the relevant groups close enough together to promote proton sharing and thereby influence enzymatic reactions.The study highlights an important distinction: proton sharing may be rare in freely hydrated molecules but could become important when biomolecules are held in the right geometry by enzymes. It also demonstrates that LJ-PES is a powerful tool for studying proton behavior in solutions. Its ultrafast and site-specific sensitivity could in future help researchers investigate proton sharing directly in more complex chemical and biological systems.<blockquote><h4>The original article</h4><h4><a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/jaaucr/article/6/6/3349/5084661/Proton-Sharing-in-Polycarboxylic-Acids-in-Aqueous">Proton Sharing in Polycarboxylic Acids in Aqueous Solution</a></h4>Lukáš Tomaník, Jiří Tůma, Gunnar Öhrwall, Ronny Golnak, Ngoc Lan Le Nguyen, Bruno Credidio, Harmanjot Kaur, Petr Slavíček, Bernd Winter, H. Christian Schewe<div>JACS Au, 2026, 6, 3349–3355</div><a target="_blank" rel="noopener noreferrer" href="https://doi.org/10.1021/jacsau.6c00377">https://doi.org/10.1021/jacsau.6c00377</a><h6>licenced under <a target="_blank" rel="noopener noreferrer" href="https://creativecommons.org/licenses/by/4.0/">CC-BY 4.0</a></h6></blockquote><h4>Abstract</h4>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.</div>

Proton sharing in polycarboxylic acids in aqueous solution

Autumn has already turned the leaves into vibrant shades, and with the end of the year approaching, we would like to thank you - before the first snowflakes arrive - for your trust, cooperation, and continued interest in our products and services.As a long-standing distributor of Thermo Scientific Finnpipette products, we know that the accuracy and reliability of laboratory results often begin with seemingly small details. Choosing the right pipette and tip is one of the first steps toward a successful analysis.That is why we have prepared an EXCLUSIVE offer to help you replenish your laboratory supplies at a more attractive price, while also thanking you for your continued cooperation and trust.<blockquote>EXCLUSIVE OFFER valid until the end of 2026<ul><li>10% off tips</li><li>10% off pipettes</li></ul>Enter the code “KAŠTANY” in your order or include it in your order e-mail.*For larger orders, an additional discount may be available.</blockquote><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/analytika_pipety_a_spicky_thermo_20c5943161.jpg" alt="analytika: Thermo Scientific Pipettes and Tips" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_analytika_pipety_a_spicky_thermo_20c5943161.jpg 146w," sizes="100vw" width="1500" height="1605"><h4>LIMITED OFFER WHILE STOCKS LAST</h4><h5>Everything ages. Precision remains.</h5>Finnpipette tips are proof of that.<h4>Tip Offer</h4><h5>FT 200 FLEX Tips</h5><ul><li>Code: L94060320</li><li>Pack size: 1,000 pcs</li><li>LOT: 20165B0</li><li>EXP: 20 June 2025</li><li>Price: CZK 1,761 (30% discount)</li></ul><h5>FT 1000 Tips</h5><ul><li>Code: L9401070</li><li>Pack size: 200 pcs/box</li><li>LOT: 20346A0</li><li>EXP: 20 December 2025</li><li>Price: CZK 464 (30% discount)</li></ul><h5>Labtip Blue Tips</h5><ul><li>Code: L94300250</li><li>Pack size: 60 pcs/rack</li><li>LOT: 21104B2</li><li>EXP: 20 April 2026</li><li>Price: CZK 206 (20% discount)</li></ul><h5>FT Filter Sterile 10 µL Tips</h5><ul><li>Code: L94052100</li><li>Pack size: 10 × 96 pcs/rack</li><li>LOT: 21136B1</li><li>EXP: 20 May 2026</li><li>Price: CZK 3,740 (20% discount)</li></ul><h4>Types of Thermo Fisher Scientific Pipette Tips</h4><h5>FILTERED</h5><ul><li>help prevent aerosol contamination,</li><li>suitable for PCR and critical samples.</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/analytika_spicky_Thermo_s_filtrem_4eb500736e.jpg" alt="analytika: Thermo Fisher Scientific Filtered Tip" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_analytika_spicky_Thermo_s_filtrem_4eb500736e.jpg 245w," sizes="100vw" width="450" height="120"><h5>NON-FILTERED</h5><ul><li>economical and high quality,</li><li>suitable for routine samples.</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/analytika_spicky_Thermo_bez_filtru_eea16c4ae1.jpg" alt="analytika: Thermo Fisher Scientific Non-Filtered Tips" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_analytika_spicky_Thermo_bez_filtru_eea16c4ae1.jpg 245w," sizes="100vw" width="442" height="147"><h5>EXTENDED-LENGTH</h5><ul><li>allow deeper access while helping reduce contamination risk,</li><li>suitable for tissue culture, media preparation, and tall laboratory vessels.</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/analytika_spicky_Thermo_prodlouzene_2005b4125f.jpg" alt="analytika: Thermo Fisher Scientific Extended-Length Tip" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_analytika_spicky_Thermo_prodlouzene_2005b4125f.jpg 245w," sizes="100vw" width="407" height="118"><h5>MICRO</h5><ul><li>improve accuracy for low-volume samples and support efficient sample transfer,</li><li>suitable for critical and valuable samples and low-volume pipetting.</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/analytika_spicky_Thermo_micro_9b5879704a.jpg" alt="analytika: Thermo Fisher Scientific Micro Tip" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_analytika_spicky_Thermo_micro_9b5879704a.jpg 245w," sizes="100vw" width="435" height="115"><h5>MACRO</h5><ul><li>improve accuracy when working with larger sample volumes,</li><li>can serve as an alternative to serological pipettes.</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/analytika_spicky_Thermo_macro_8fb12684a7.jpg" alt="analytika: Thermo Fisher Scientific Macro Tip" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_analytika_spicky_Thermo_macro_8fb12684a7.jpg 245w," sizes="100vw" width="395" height="121"><h5>WIDE-BORE</h5><ul><li>the wide opening helps prevent cell lysis and improves accuracy when working with viscous solutions,</li><li>suitable for cell handling, macromolecular structures such as DNA, and highly viscous solutions.</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/analytika_spicky_Thermo_siroky_otvor_9d6ad5537e.jpg" alt="analytika: Thermo Fisher Scientific Wide-Bore Tip" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_analytika_spicky_Thermo_siroky_otvor_9d6ad5537e.jpg 245w," sizes="100vw" width="397" height="127">

Equip Your Laboratory for Autumn at a Better Price

Breathomics, Asthma & GC×GC: PH Stefanuto on Fighting the “Proof‑of‑Concept” Trap

Article

Product

Video

Scientists

Interview

Science and research

The Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences (IOCB Prague) is a leading scientific institution in the Czech Republic, recognized internationally. Its primary mission is basic research in the fields of chemical biology and medicinal chemistry, organic and material oriented chemistry, chemistry of natural compounds, biochemistry and molecular biology, physical chemistry, theoretical chemistry, and analytical chemistry. 

Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences

Analytika is a Czech company that offers and produces certified reference materials (CRM) and (ultra)pure chemicals for quality control and quality assurance in laboratories, including accredited laboratories.

Our portfolio also includes pipettes and tips, digestors, PFA labware and other equipment for analytical laboratory and trace analysis.

ANALYTIKA

Organomation, founded in 1959, designs and manufactures high-quality nitrogen evaporators and extraction systems. Known for innovation and durability, their lab instruments are used globally for efficient sample preparation with strong customer support.

Organomation

Modern HPLC separations in theory and practice

This book is a unique combination of theory and practice, but also overviews of stationary phases, sample prep materials, and vendor’s brief presentations.

The Fitness for Purpose of Analytical Methods

The third edition of Eurachem’s flagship guide provides updated, practical guidance on method validation, verification, sampling, and fitness for purpose, aligned with ISO/IEC 17025:2017.

<h3>The Fitness for Purpose of Analytical Methods: A Laboratory Guide to Method Validation and Related Topics: Third edition (2025)</h3>Author: H. CantwellThis guide was first issued in 1998 and the second edition published in 2014. Over the years it has been one of the most popular of the Eurachem guides. Since the release of the first edition, however, there have been many changes in terminology, working practices, reference documents and requirements. This third edition, produced by the Eurachem Method Validation Working Group, forms a thorough revision of the 2014 edition.This third edition includes a section on sampling and sample handling as ISO/IEC 17025:2017 introduced a focus on sampling associated with the testing or calibration being carried out by the laboratory and further guidance on assessing the calibration function has been included. The Guide is also now supported by a number of supplementary guidance documents – please see the section on supplementary guidance below.<h4>Contents</h4>This third edition includes guidance on:<ul><li>The importance of fitness for purpose;</li><li>The concept of method validation and verification;</li><li>How a method validation or verification study should be performed and how much should be done;</li><li>Sampling and sample handling in relation to method validation;</li><li>A thorough explanation of the various validation parameters (performance characteristics) and related topics;</li><li>Follow-up on the validation study (reporting, use of performance data in Internal Quality Control);</li><li>Documentation of analytical methods.</li></ul>Annexes also describe the statistical basis of detection limits and analysis of variance for precision studies, and add a check list to aid users in selecting and determining the validity of a test kit.In preparing this guidance, the Working Group has aimed at the right balance between giving a solid theoretical background for method validation studies and providing practical guidelines on how to plan, perform and evaluate such studies in the laboratories.The approach is generic in the sense that the Guide does not focus on particular fields of application (food, environment, pharmaceuticals etc.). However, the guide includes references to a number of specific guides in fields where different practices have been developed and become common.The guide also includes a full bibliography. Further literature references on method validation can be found in the section "Validation of analytical methods" in the Reading list on this website.

Terminology in Analytical Measurement: Introduction to VIM 3

This Eurachem guide introduces VIM 3 terminology relevant to analytical laboratories, explaining key metrological concepts for chemical, biological, and clinical measurements with practical examples.

<h3>Terminology in Analytical Measurement: Introduction to VIM 3 (Second Edition 2023)</h3>Author: V. J. Barwick (Ed.)<h4>Contents</h4>This guide has been produced by members of the Eurachem Education and Training Working Group and others co-opted to the Project group for this task.In the world of metrology – the science of measurement and its application – there is a language which has to be learned. The International Vocabulary of Metrology (VIM) was produced to provide a common language, primarily for physical measurements. The VIM 3 is a consistent set of concepts each described by a unique term, the ‘label’ of the concept. VIM 3 is applicable across all scientific disciplines thus making it relevant to those involved in performing measurements in chemistry and biology. Consistent definitions of concepts with their associated terms and symbols are essential if analysts and customers across the globe are to understand each other.This Eurachem Guide discusses a selection of the concepts in VIM 3, focusing on those most likely to be encountered in analytical laboratories. It aims to cover chemical, biological and clinical measurements and gives examples over and above those in the notes accompanying the definitions in VIM 3. The guide is intended for laboratory staff, accreditation bodies, for those commissioning measurements and for those using measurement results. Lecturers and trainers may also find this guide useful when teaching aspects of metrology.In this second edition the scope and structure, and the terms and concepts discussed, remain unchanged from the first edition. However, all sections have been reviewed and, where necessary, the text has been revised to improve clarity and ensure consistency with current international guidance at the time of publication.

Products from category Educational literature - page 1

Related content

Breathomics, Asthma & GC×GC: PH Stefanuto on Fighting the “Proof‑of‑Concept” Trap

Proton sharing in polycarboxylic acids in aqueous solution

Equip Your Laboratory for Autumn at a Better Price