<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.

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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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Organomation H Series Hydrogen Generator

The H Series Hydrogen Generator delivers up to 600 mL/min hydrogen with 99.9999% purity, advanced safety features, and scalable modular design.

The Organomation H Series Hydrogen Generator is a modular hydrogen generation system designed for GC, GC-MS (GC-MSD), and FAST GC applications. It is available in three models with flow rates of 200, 400, and 600 mL/min, delivering ultra-high purity hydrogen up to 99.9999%.The system uses HT PEM electrolytic cell technology, producing hydrogen on demand, minimizing internal gas storage and enhancing safety.A comprehensive safety system includes acoustic alarms, display messages, and automatic shutdown in case of gas leaks, with automatic switching to inert gas if hydrogen production stops.The generator features a touchscreen CPU, supports CAN-BUS and LAN connectivity, and allows real-time monitoring, diagnostics, and maintenance management. Up to four units can be connected in parallel for scalable performance.<h4>Key Features</h4><ul><li>Three models: 200 / 400 / 600 mL/min</li><li>Hydrogen purity up to 99.9999% (UHP)</li><li>HT PEM electrolytic cell technology</li><li>On-demand hydrogen production</li><li>Advanced safety system with alarms and auto shutdown</li><li>Automatic switch to inert gas</li><li>Removable water tank for easy maintenance</li><li>Low maintenance and low operating cost</li><li>Parallel connection of up to 4 units</li><li>Touchscreen CPU with CAN-BUS and LAN</li><li>Full monitoring of system status and alarms</li></ul><h4>Available Models</h4><h5>H Series 200</h5><ul><li>Flow rate: 200 mL/min ±10%</li><li>Power consumption: 110 W</li></ul><h5>H Series 400</h5><ul><li>Flow rate: 400 mL/min ±10%</li><li>Power consumption: 180 W</li></ul><h5>H Series 600</h5><ul><li>Flow rate: 600 mL/min ±10%</li><li>Power consumption: 250 W</li></ul><h4>Standard Features</h4><ul><li>HT PEM electrolytic cell</li><li>Touchscreen CPU</li><li>LAN connectivity</li><li>CAN-BUS communication</li><li>Removable water tank</li><li>Automatic water refill pump</li><li>Safety system with alarms and auto shutdown</li><li>Automatic inert gas switching</li><li>Modular stackable configuration</li></ul><h3>Technical Specifications</h3><h4>General</h4><ul><li>Technology: HT PEM electrolytic cell</li><li>Purity: 99.9999%</li><li>Oxygen: &lt; 1 ppm</li><li>Dew point: &lt; -70°C</li><li>Output pressure: 2–8 bar (30–116 psi)</li><li>Max altitude: 2000 m</li><li>Noise: &lt; 50 dBA</li><li>Protection class: IP20</li></ul><h4>Electrical</h4><ul><li>115/230 V, 50–60 Hz</li><li>H200: 110 W</li><li>H400: 180 W</li><li>H600: 250 W</li></ul><h4>Operating Conditions</h4><ul><li>Temperature: 5–35 °C</li><li>Humidity: max 90% non-condensing</li></ul><h4>Water Requirements</h4><ul><li>Minimum resistivity: &gt;1 MΩ·cm (ASTM II)</li><li>Recommended: &lt;10 MΩ·cm (ASTM I)</li></ul><h4>Dimensions &amp; Weight</h4><ul><li>Dimensions: 47 × 38 × 53 cm</li><li>Weight: 30 kg</li></ul><h4>Connections</h4><ul><li>Hydrogen output: G 1/8" female (AISI 316)</li><li>Exhaust: 4 mm quick connector</li><li>Water input: 1/4" connection</li></ul><h4>Warranty</h4><ul><li>2 years</li></ul><h4>Accessories</h4><ul><li>Water demineralizer</li><li>Maintenance kit (9,000 / 18,000 hours)</li><li>Water refill pump</li></ul>

Organomation HG 2200 R Hydrogen Generator

The Organomation HG 2200 R delivers up to 200 mL/min hydrogen with >99.999% purity, low noise, and easy maintenance for THC analyzers.

The Organomation HG 2200 R is a compact hydrogen generator designed for THC and emission monitoring analyzers. It delivers flow rates up to 200 mL/min with hydrogen purity greater than 99.999%, and oxygen content below 0.1 ppm when used with additional purifiers.The unit allows adjustable outlet pressure from 1 to 4 bar (up to 6 bar on demand) and features a removable external water tank for easy maintenance. An automatic water loading pump supports continuous operation.<h4>Key Features</h4><ul><li>Hydrogen flow up to 200 mL/min</li><li>Purity &gt;99.999% (UHP)</li><li>O₂ &lt;0.1 ppm with additional purifier</li><li>Adjustable outlet pressure: 1–4 bar (up to 6 bar)</li><li>Removable water tank for easy cleaning</li><li>Optional continuous water supply (pump)</li><li>Low noise level &lt;46 dB</li><li>Compact benchtop design</li><li>Simple operation and maintenance</li></ul><h4>Standard Features</h4><ul><li>UHP hydrogen generation (&gt;99.999%)</li><li>Pressure control via keyboard</li><li>Removable water tank</li><li>External water supply capability</li><li>Integrated dryer with molecular sieve</li></ul><h3>Technical Specifications</h3><h4>General</h4><ul><li>Model: HG 2200 R</li><li>Flow rate: 200 mL/min</li><li>Purity: &gt;99.999%</li><li>Oxygen content: &lt;0.1 ppm (with purifier)</li></ul><h4>Output Pressure</h4><ul><li>Standard: 1–4 bar</li><li>Maximum: 6 bar (on request)</li></ul><h4>Electrical</h4><ul><li>115/230 V, 50–60 Hz</li><li>Power rating: 100 VA</li></ul><h4>Operating Conditions</h4><ul><li>Temperature: 5–40 °C</li><li>Noise level: &lt;46 dB</li></ul><h4>Water Requirements</h4><ul><li>Demineralized water ≤ 5 µS/cm (~0.2 MΩ·cm)</li></ul><h4>Consumables</h4><ul><li>Dryer with molecular sieve</li></ul><h4>Dimensions &amp; Weight</h4><ul><li>Dimensions: 31 × 48 × 38 cm</li><li>Weight: 20 kg</li></ul><h4>Warranty</h4><ul><li>1 year</li></ul><h4>Accessories / Options</h4><ul><li>Additional purifiers for ultra-low O₂</li><li>Water refill pump</li></ul>

Products from category Hydrogen generators distributed by Organomation - page 1

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

Proton sharing in polycarboxylic acids in aqueous solution

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