Heme is a vital cofactor of proteins with roles in oxygen transport (e.g. hemoglobin), storage (e.g. myoglobin), and activation (e.g. P450) as well as electron transfer (e.g. cytochromes) and many other functions. However, its structural and functional role in oxygen sensing proteins differs markedly from that in most other enzymes, where it serves as a catalytic or functional center. This minireview discusses the mechanism of signal transduction in two heme-based oxygen sensors: the histidine kinase AfGcHK and the diguanylate cyclase YddV (EcDosC), both of which feature a heme-binding domain containing a globin fold resembling that of hemoglobin and myoglobin.

• Klíčová slova
• globin-coupled sensors, heme, heme-based sensor proteins, hemoproteins, oxygen sensors, signal transduction,
• MeSH
• hem * chemie   MeSH
• hemoglobiny MeSH
• histidinkinasa chemie   metabolismus   MeSH
• kyslík metabolismus   MeSH
• myoglobin * metabolismus   MeSH
• signální transdukce MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• diguanylate cyclase MeSH Prohlížeč
• hem * MeSH
• hemoglobiny MeSH
• histidinkinasa MeSH
• kyslík MeSH
• myoglobin * MeSH

Reactive oxygen species (ROS) involving superoxide anion, hydrogen peroxide and hydroxyl radical play important role in human health. ROS are known to be the markers of oxidative stress associated with different pathologies including neurodegenerative and cardiovascular diseases, as well as cancer. Accordingly, ROS level detection in biological systems is an essential problem for biomedical and analytical research. Electrochemical methods seem to have promising prospects in ROS determination due to their high sensitivity, rapidity, and simple equipment. This review demonstrates application of modern electrochemical sensors for ROS detection in biological objects (e.g., cell lines and body fluids) over a decade between 2011 and 2021. Particular attention is paid to sensors materials and various types of modifiers for ROS selective detection. Moreover, the sensors comparative characteristics, their main advantages, disadvantages and their possibilities and limitations are discussed.

• Klíčová slova
• Biological objects, body fluid, cell, electrochemical sensor, reactive oxygen species,
• MeSH
• biosenzitivní techniky přístrojové vybavení   metody   MeSH
• elektrochemické techniky * přístrojové vybavení   MeSH
• lidé MeSH
• oxidační stres MeSH
• reaktivní formy kyslíku * analýza   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• reaktivní formy kyslíku * MeSH

An emerging class of novel heme-based oxygen sensors containing a globin fold binds and senses environmental O2 via a heme iron complex. Structure-function relationships of oxygen sensors containing a heme-bound globin fold are different from those containing heme-bound PAS and GAF folds. It is thus worth reconsidering from an evolutionary perspective how heme-bound proteins with a globin fold similar to that of hemoglobin and myoglobin could act as O2 sensors. Here, we summarize the molecular mechanisms of heme-based oxygen sensors containing a globin fold in an effort to shed light on the O2-sensing properties and O2-stimulated catalytic enhancement observed for these proteins.

• Klíčová slova
• Chemotaxis, Cyclic GMP (cGMP), Heme, Hemoglobin, Histidine Kinases, Myoglobin, Oxygen Binding,
• MeSH
• Azotobacter vinelandii enzymologie   MeSH
• Bordetella pertussis enzymologie   MeSH
• chemotaxe MeSH
• Escherichia coli enzymologie   MeSH
• globiny chemie   MeSH
• hem chemie   MeSH
• hemoglobiny chemie   MeSH
• histidinkinasa MeSH
• katalytická doména MeSH
• katalýza MeSH
• kyslík chemie   MeSH
• lyasy štěpící vazby P-O chemie   MeSH
• molekulární evoluce MeSH
• molekulární sekvence - údaje MeSH
• myoglobin chemie   MeSH
• proteinkinasy chemie   MeSH
• proteiny z Escherichia coli chemie   MeSH
• regulace genové exprese enzymů * MeSH
• sekvence aminokyselin MeSH
• sekvenční homologie aminokyselin MeSH
• vazba proteinů MeSH
• vazebná místa MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• diguanylate cyclase MeSH Prohlížeč
• globiny MeSH
• hem MeSH
• hemoglobiny MeSH
• histidinkinasa MeSH
• kyslík MeSH
• lyasy štěpící vazby P-O MeSH
• myoglobin MeSH
• proteinkinasy MeSH
• proteiny z Escherichia coli MeSH

Bacterial oxygen sensing embodies a fascinating interplay between evolutionary pressures and physiological adaptations to varying oxygen levels. Throughout Earth's history, the composition of the atmosphere has undergone significant changes, from anoxic conditions to the gradual accumulation of oxygen. In response, microbial life has evolved diverse strategies to cope with these shifting oxygen levels, ranging from anaerobic metabolism to oxygen-dependent pathways crucial for energy production and cellular processes typical for eukaryotic, multicellular organisms. Of particular interest is the role of iron in bacterial oxygen sensing systems, which play pivotal roles in adaptation to changing oxygen levels. Only free iron, heme-iron, and non-heme iron directly sense oxygen. These iron-containing proteins, such as heme-containing sensors and iron-sulfur cluster proteins, regulate the expression of genes and activity of enzymes involved in oxidative stress defence, virulence, and biofilm formation, highlighting their significance in bacterial pathogenesis and environmental adaptation. Special attention in the review is paid to the mechanisms of oxygen detection and signal transduction from heme-containing sensing to functional domains in the case of bacterial heme-based oxygen sensors.

• Klíčová slova
• Heme-based sensor, Intramolecular catalytic regulation, Oxygen sensing, Signal transduction,
• MeSH
• Bacteria * metabolismus   genetika   MeSH
• bakteriální proteiny metabolismus   genetika   MeSH
• fyziologie bakterií * MeSH
• hem * metabolismus   MeSH
• hemoproteiny metabolismus   MeSH
• kyslík * metabolismus   MeSH
• regulace genové exprese u bakterií MeSH
• signální transdukce MeSH
• železo * metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• bakteriální proteiny MeSH
• hem * MeSH
• hemoproteiny MeSH
• kyslík * MeSH
• železo * MeSH

The nonradioactive method, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) in the presence of Phos-tag (Phos-tag electrophoresis), is used to evaluate a kinase autophosphorylation and/or phosphotransfer reaction from a kinase/ATP to its protein substrate. This method outperforms radioisotope methods using [32P]ATP for detecting trace amounts of phosphorylated protein in fresh protein preparations. Phos-tag electrophoresis has been used to perform detailed analyses of the kinase activity of a heme-based oxygen sensor-specifically, a globin-coupled histidine kinase from the soil bacterium Anaeromyxobacter sp. Fw109-5 (AfGcHK).

• Klíčová slova
• Autophosphorylation reaction, Heme-based oxygen sensors, Kinase activity, Ligand binding, Ligand-dependent kinase activity, Phos-tag electrophoresis, Phosphotransfer reaction,
• MeSH
• adenosintrifosfát metabolismus   MeSH
• Bacteria metabolismus   MeSH
• elektroforéza v polyakrylamidovém gelu MeSH
• hem * metabolismus   MeSH
• kyslík metabolismus   MeSH
• ligandy MeSH
• proteiny * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 1,3-bis(bis(pyridin-2-ylmethyl)amino)propan-2-ol MeSH Prohlížeč
• adenosintrifosfát MeSH
• hem * MeSH
• kyslík MeSH
• ligandy MeSH
• proteiny * MeSH

Despite having been commercially available for more than half a century, conductometric gas sensors still lack a definite description of their operation mechanism, which hinders research into improving their characteristics. With the advent of operando spectroscopy comes the opportunity to elucidate their working principle by observing their surface during sensing. To that end, we have employed near-ambient pressure (NAP) XPS with simultaneous resistance measurements to correlate the macroscopic sensor response with atomistic changes to the sensor's surface under exposure to CO, a common target gas. Our results show a clear relationship between the sensor response and the change in surface stoichiometry of SnO2, suggesting that near-surface oxygen vacancies play a vital role in the sensing mechanism, in support of a vacancy-modulated "surface conductivity" mechanism.

• Klíčová slova
• NAP-XPS, conductometric, mechanism, resistance, sensor, spectroscopy, vacancy,
• MeSH
• fotoelektronová spektroskopie MeSH
• kyslík * chemie   MeSH
• oxid uhelnatý * analýza   chemie   MeSH
• plyny * analýza   MeSH
• povrchové vlastnosti MeSH
• sloučeniny cínu * chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• kyslík * MeSH
• oxid uhelnatý * MeSH
• plyny * MeSH
• sloučeniny cínu * MeSH
• stannic oxide MeSH Prohlížeč

Implantable medical devices are an integral part of primary/critical care. However, these devices carry a high risk for blood clots, caused by platelet aggregation on a foreign body surface. This study focuses on the development of a simplified approach to create nitric oxide (NO) releasing intravascular electrochemical oxygen (O2) sensors with increased biocompatibility and analytical accuracy. The implantable sensors are prepared by embedding S-nitroso-N-acetylpenacillamine (SNAP) as the NO donor molecule in the walls of the catheter type sensors. The SNAP-impregnated catheters were prepared by swelling silicone rubber tubing in a tetrahydrofuran solution containing SNAP. Control and SNAP-impregnated catheters were used to fabricate the Clark-style amperometric PO2 sensors. The SNAP-impregnated sensors release NO under physiological conditions for 18 d as measured by chemiluminescence. The analytical response of the SNAP-impregnated sensors was evaluated in vitro and in vivo. Rabbit and swine models (with sensors placed in both veins and arteries) were used to evaluate the effects on thrombus formation and analytical in vivo PO2 sensing performance. The SNAP-impregnated PO2 sensors were found to more accurately measure PO2 levels in blood continuously (over 7 and 20 h animal experiments) with significantly reduced thrombus formation (as compared to controls) on their surfaces.

• Klíčová slova
• Biocompatible, Implantable oxygen sensor, Nitric oxide,
• MeSH
• arteria femoralis MeSH
• cévní přístupy * MeSH
• design vybavení MeSH
• donory oxidu dusnatého chemie   MeSH
• elektrochemické techniky přístrojové vybavení   metody   MeSH
• králíci MeSH
• kyslík krev   MeSH
• luminiscenční měření MeSH
• oxid dusnatý farmakokinetika   MeSH
• prasata MeSH
• S-nitroso-N-acetylpenicilamin chemie   MeSH
• silikony MeSH
• zvířata MeSH
• Check Tag
• králíci MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• donory oxidu dusnatého MeSH
• kyslík MeSH
• oxid dusnatý MeSH
• S-nitroso-N-acetylpenicilamin MeSH
• silikony MeSH

The primary function of spermatozoa is to fertilize the oocyte, which depends on their motility and is directly associated with their metabolic state. The oxygen consumption rate (OCR) of spermatozoa reflects the respiratory capacity of sperm mitochondria under various physiological conditions and is an essential marker of sperm quality. We determined the OCR of common carp (Cyprinus carpio) sperm using two respirometry methods: the conventionally used polarographic method with a Clark-type electrode and fluorometric assay with an Oxo Dish optochemical oxygen sensor. The latter was used for the first time to evaluate spermatozoa oxygen consumption in various metabolic states (under different treatments) at different dilution rates. These two methods were compared using Bland-Altman analysis, and the applicability of the optochemical oxygen sensor for evaluating carp sperm oxygen consumption was discussed. Sperm motility and progressive velocity parameters were also assessed to evaluate the effect of sperm respiration under different metabolic states and dilution rates and preincubation period on the physiological status of spermatozoa. The comparison of these respirometry methods clearly shows that while the polarographic method allows immediate measurement of oxygen levels after adding a sperm sample, the optochemical oxygen sensor has a priority in the amount of data obtained due to simultaneous measurements of several samples (e.g., different males, different fish species, repetitions of the same sample or various experimental conditions), even at a later time after adding sperm to the measuring chamber. However, the compared methods are complementary, and the proposed methodology can be applied to other fish species.

• Klíčová slova
• Clark-type electrode, Common carp, Optochemical oxygen sensor, Oxygen consumption rate, Sperm motility, Spermatozoa,
• MeSH
• buněčné dýchání fyziologie   MeSH
• fluorometrie * metody   veterinární   přístrojové vybavení   MeSH
• kapři * fyziologie   metabolismus   MeSH
• kyslík metabolismus   MeSH
• motilita spermií fyziologie   MeSH
• polarografie * metody   přístrojové vybavení   veterinární   MeSH
• spermie * fyziologie   MeSH
• spotřeba kyslíku * fyziologie   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• kyslík MeSH

Hydrogen/deuterium exchange (HDX) is a well-established analytical technique that enables monitoring of protein dynamics and interactions by probing the isotope exchange of backbone amides. It has virtually no limitations in terms of protein size, flexibility, or reaction conditions and can thus be performed in solution at different pH values and temperatures under controlled redox conditions. Thanks to its coupling with mass spectrometry (MS), it is also straightforward to perform and has relatively high throughput, making it an excellent complement to the high-resolution methods of structural biology. Given the recent expansion of artificial intelligence-aided protein structure modeling, there is considerable demand for techniques allowing fast and unambiguous validation of in silico predictions; HDX-MS is well-placed to meet this demand. Here we present a protocol for HDX-MS and illustrate its use in characterizing the dynamics and structural changes of a dimeric heme-containing oxygen sensor protein as it responds to changes in its coordination and redox state. This allowed us to propose a mechanism by which the signal (oxygen binding to the heme iron in the sensing domain) is transduced to the protein's functional domain.

• Klíčová slova
• Globin-coupled histidine kinase, Heme-containing oxygen sensors, Hydrogen/deuterium exchange, Ligand binding, Mass spectrometry, Protein conformational dynamics, Signal transduction,
• MeSH
• deuterium MeSH
• hem chemie   MeSH
• hemoproteiny * MeSH
• hmotnostní spektrometrie metody   MeSH
• kyslík metabolismus   MeSH
• umělá inteligence MeSH
• vodík-deuteriová výměna metody   MeSH
• vodík chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• deuterium MeSH
• hem MeSH
• hemoproteiny * MeSH
• kyslík MeSH
• vodík MeSH

BACKGROUND: There is considerable interest in oxygen partial pressure (Po2) monitoring in physiology, and in tracking Po2 changes dynamically when it varies rapidly. For example, arterial Po2 ([Formula: see text]) can vary within the respiratory cycle in cyclical atelectasis (CA), where [Formula: see text] is thought to increase and decrease during inspiration and expiration, respectively. A sensor that detects these [Formula: see text] oscillations could become a useful diagnostic tool of CA during acute respiratory distress syndrome (ARDS). METHODS: We developed a fibreoptic Po2 sensor (<200 µm diameter), suitable for human use, that has a fast response time, and can measure Po2 continuously in blood. By altering the inspired fraction of oxygen ([Formula: see text]) from 21 to 100% in four healthy animal models, we determined the linearity of the sensor's signal over a wide range of [Formula: see text] values in vivo. We also hypothesized that the sensor could measure rapid intra-breath [Formula: see text] oscillations in a large animal model of ARDS. RESULTS: In the healthy animal models, [Formula: see text] responses to changes in [Formula: see text] were in agreement with conventional intermittent blood-gas analysis (n=39) for a wide range of [Formula: see text] values, from 10 to 73 kPa. In the animal lavage model of CA, the sensor detected [Formula: see text] oscillations, also at clinically relevant [Formula: see text] levels close to 9 kPa. CONCLUSIONS: We conclude that these fibreoptic [Formula: see text] sensors have the potential to become a diagnostic tool for CA in ARDS.

• Klíčová slova
• acute respiratory distress syndrome, arterial oxygen monitoring, cyclical atelectasis, fibreoptic sensor,
• MeSH
• kyslík krev   MeSH
• modely nemocí na zvířatech MeSH
• prasata MeSH
• syndrom dechové tísně krev   MeSH
• technologie optických vláken MeSH
• zvířata MeSH
• Check Tag
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• kyslík MeSH