<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

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

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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.

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SIELC Alltesta Mini HPLC Autosampler

The Alltesta™ Mini Autosampler is an affordable and dependable solution for automated sample handling in various analytical and liquid handling applications, including HPLC.

The Alltesta™ Mini Autosampler is an affordable and dependable solution for automated sample handling in various analytical and liquid handling applications, including HPLC. With its proprietary alpha/beta mechanical design, this compact autosampler offers direct and comprehensive control of its features, making integration quick and easy. Users can tailor the mini autosampler to their needs with customizable valve configurations, tray designs, and syringe volumes and pressures. Additionally, a built-in shaking feature enables sample mixing before injection and/or simple sample extraction within the vial.
This compact autosampler comes designed with original equipment manufacturer (OEM) customization in mind. Custom shape, color, and communication interfaces can be adapted to integrate with any system. Comprehensive software integration support is provided. Other options include metal-free sampling and reagent addition and mixing capabilities.
<ul>
<li>FRACTION COLLECTION CAPABILITY: A simple software modification can quickly convert this small autosampler into a fraction collector.
</li>
<li>REACTOR PROBE SAMPLER CAPABILITY: A simple software modification can quickly convert this small autosampler into a reactor probe sampler.
</li>
</ul>
This miniature autosampler can also be used as a component of our <a href="https://lcms.labrulez.com/products/1242">Alltesta™ Gradient Automated Analyzer</a> and <a href="https://lcms.labrulez.com/products/1243">Alltesta™ Cromite Analyzer</a>.
<blockquote>
<h4>The price of the Alltesta™ Mini Autosampler varies depending on the specific configuration requested.</h4>
</blockquote>
<h4>Specifications</h4>
<ul>
<li>Dimensions (WHL): 160 x 145 x 195 mm / 6.3 x 5.71 x 7.68 in</li>
<li>Weight: 3 kg / 6.6 lb</li>
<li>Power: 24 V</li>
<li>Capacity: 48 vials or 96-well plate</li>
<li>Pressure: 5000 psi</li>
<li>Needle Wash: Inside and outside</li>
<li>Syringe Capacity: 120µL high-pressure / 4000µL low-pressure stainless / 4000µL low-pressure ceramic</li>
<li>Valve options: 6×2, 7×6 and 10×9 (more details here).</li>
<li>Volume Accuracy: 0.1µL</li>
<li>Communication: RS232 Virtual COM port via USB</li>
</ul>
<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/SIELC_Alltesta_Mini_Autosampler_A_very_simple_schematic_operation_of_the_Alltesta_Autosampler_b79b0ad187.jpg" alt="SIELC: Alltesta™ Mini Autosampler - A very simple schematic operation of the Alltesta™ Autosampler."/>
<h4>Software</h4>
The Alltesta™ Autosampler can be controlled:
<ul>
<li>directly via serial commands (Alltesta™ protocol available upon request, please contact us at support@sielc.com),</li>
<li>directly via our demo software, allowing to learn the whole functionality of the unit (<a href="https://sielc.com/wp-content/uploads/2022/12/Alltesta_Autosampler_Control_Windows_10.zip">Windows 10, 32/64bit</a>, 5Mb; <a href="https://sielc.com/wp-content/uploads/2022/12/Alltesta_Autosampler_Control_Windows_7.zip">Windows 7, 32/64bit</a>, 126Mb).</li>
<li>remotely through our cloud software (as a part of Alltesta™ Analyzer or Alltesta™ Mini Analyzer),</li>
</ul>
Serial communication drivers are available <a href="https://ftdichip.com/drivers/vcp-drivers/">here</a>.

Watrex Streamline FC1 Fraction Collector

The fully automated fraction collector FC1 offers a universal solution for a number of applications requiring the collection of fractions, e.g. protein purification, preparative chromatography.

The fully automated fraction collector FC1 offers a universal solution for a number of applications requiring the collection of fractions, e.g. protein purification, preparative chromatography or other methods for obtaining samples by fractionation.<blockquote>Price: 4 260<bdi>&nbsp;€ ex VAT</bdi></blockquote>For advanced programming and connection to chromatography software, the device is equipped with a USB interface. FC1 is supported by the <a target="_blank" rel="noopener noreferrer" href="https://lcms.cz/products/305">Clarity Chromatography Station</a><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Watrex_schema_procesu_sberu_frakci_pomoci_frakcni_kolektor_FC_1_fa579d59f2/Watrex-schema-procesu-sberu-frakci-pomoci-frakcni-kolektor-FC1.png" alt="Watrex: Schematic of the fraction collection process using the FC1 fraction collector">The robust design of the FC1 ensures reliable X-Y displacement that carries the switching valve. Placing the fraction switch directly above the receiving vessel minimizes dead volume between fractions.Depending on the required volume of fractions, different types of test tube stands are offered with the device. Furthermore, it is also possible to use large-volume containers.The operator controls and programs the fraction collector from the touch screen on the front panel of the device using intuitively arranged screens with adjustable parameters for a given fraction collection series.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Watrex_Nastaveni_treshold_limitu_pro_sber_frakci_pomoci_sberace_frakci_FC_1_f48d645dfc/Watrex-Nastaveni-treshold-limitu-pro-sber-frakci-pomoci-sberace-frakci-FC1.jpg" alt="Watrex: Setting the treshold limit for fraction collection using the FC1 fraction collector"><h3>FEATURES</h3><ul><li>Simple operation</li><li>Color touch panel control</li><li>Optional analog input</li><li>Selection of rack types</li><li>Clarity CDS supported</li></ul><h3>TECHNICAL SPECIFICATION</h3><ul><li>Max. flow: 50 ml/min</li><li>Wetted Materials: PTFE, PEEK</li><li>User control: Color touch panel</li><li>PC connection: USB</li><li>External control: TTL (contact closure) - RUN, STOP, NEXT, COLLECT</li><li>Power supply: 24V DC external power supply</li></ul><h3>Ordering information:</h3><h5>PN/Component:</h5><ul><li>SFC101-001 Streamline™ FC1 Fraction Collector</li><li>SFC101-002 Cooling option for FC1 Fraction Collector</li><li>SFC101-003 Analog Signal Monitoring, Input for FC1 Fraction Collector</li></ul>You can also visit this product on the <a target="_blank" rel="noopener noreferrer" href="https://watrex.com/obchod/chromatography/dedicated-instruments/streamline-fc1-fraction-collector/?utm_source=labrulez&amp;utm_medium=propagace&amp;utm_campaign=labrulez_produkty">Watrex website</a>.

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Proton sharing in polycarboxylic acids in aqueous solution

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