The structural basis of inhibitory effect of organic solvent dimethyl sulfoxide (DMSO) on human acetylcholinesterase (EC 3.1.1.7; hAChE) was inferred from the effect of DMSO on kinetics of reversible inhibition of uncharged, heterocyclic bis-oximes to hAChE, from DMSO effect on rates of reactivation of inactive organophosphate (OP)-hAChE conjugates by bis-oximes and by X-ray structures of bis-oxime and DMSO binding to hAChE. The reversible inhibition constant of DMSO for hAChE in 0.1 M phosphate buffer pH 7.4 at 22 °C, was Ki= (0.32 ± 0.04) % (or 45 ± 5 mM). The Ki of the bis-oxime LG-703 for hAChE was 3.2-fold larger in 1 % DMSO, consistent with direct competition between LG-703 and DMSO. The X-ray structure of the LG-703∗hAChE complex (PDB ID: 6U3P) shows DMSO and LG-703 bound to individual hAChE monomers, LG-703 in the chain A and DMSO in the chain B. In the co-crystallization both small molecules were present at a similar excess over their corresponding Ki values for hAChE (7.8-fold for DMSO and 6.5-fold for LG-703) and formation of two different complexes (DMSO∗hAChE and LG-703∗hAChE), in the same crystal, appears consistent with inhibition kinetics. Furthermore, rates of reactivation of paraoxon-inhibited hAChE (POX-hAChE) and of VX-hAChE by LG-703 and by a novel heterocyclic bis-oxime LG-1922 were reduced 2 - 3-fold in DMSO, consistent with observation of the active-center-bound DMSO molecules in the newly solved structure of the LG-1922∗POX-hAChE complex presented here and in our POX-hAChE structure (PDB ID: 8DT2) showing obstruction of the reactivator access to the conjugated P atom.

• Klíčová slova
• Acetylcholinesterase inhibition, Acetylcholinesterase reactivation, Antidotes, DMSO, Heterocyclic bis-oximes, Organic solvent, Organophosphorus compounds, Paraoxon, VX,
• MeSH
• acetylcholinesterasa * metabolismus   chemie   MeSH
• cholinesterasové inhibitory chemie   farmakologie   metabolismus   MeSH
• dimethylsulfoxid * chemie   farmakologie   metabolismus   MeSH
• kinetika MeSH
• krystalografie rentgenová MeSH
• lidé MeSH
• oximy * chemie   metabolismus   farmakologie   MeSH
• vazba proteinů MeSH
• vazebná místa MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• acetylcholinesterasa * MeSH
• cholinesterasové inhibitory MeSH
• dimethylsulfoxid * MeSH
• oximy * MeSH

Andrographolide (1) is a labdane-type diterpene lactone and the major bioactive metabolite (2.39%) in the leaves of Andrographis paniculata (Acanthaceae). To further explore its stability, the thermal degradation kinetics of compound 1 at pH 2.0, pH 6.0, and pH 8.0 were modeled at three temperatures within 50-85 °C. The activation energy (Ea), shelf-life (t90%), and rate constant (k) for compound 1 were determined using the Arrhenius equation. Consequently, the results indicated that degradation followed first-order kinetics, and the optimum pH for stability was determined to be between pH 2.0 and 4.0. Major degradation products formed under pH 2.0 and pH 6.0 conditions were isolated and spectroscopically characterized by comparison with known compounds. Under pH 2.0 conditions, two degradation products were identified: isoandrographolide (2) and 8,9-didehydroandrographolide (3). Under pH 6.0 conditions, three degradation products were formed: 15-seco-andrographolide (4), 14-deoxy-15-methoxyandrographolide (5), and 11,14-dehydro-14-deoxyandrographolide (6). Anti-inflammatory and cytotoxicity assessments demonstrated reduced biological effects for the degradation products compared with compound 1. This highlights the importance of controlling pH during formulation to ensure product stability, sustained bioactivity, and patient benefit.

• Klíčová slova
• Andrographolide, Arrhenius equation, Cytotoxicity, Degradation, NO production, Product characterization, pH dependency,
• MeSH
• Andrographis chemie   MeSH
• antiflogistika farmakologie   chemie   MeSH
• diterpeny * chemie   farmakologie   MeSH
• kinetika MeSH
• koncentrace vodíkových iontů MeSH
• lidé MeSH
• listy rostlin chemie   MeSH
• myši MeSH
• stabilita léku MeSH
• teplota MeSH
• voda chemie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• andrographolide MeSH Prohlížeč
• antiflogistika MeSH
• diterpeny * MeSH
• voda MeSH

Tau aggregation into neurofibrillary tangles is a defining feature of Alzheimer's disease and other tauopathies. Although aggregation depends largely on specific amyloidogenic motifs (particularly VQIINK and VQIVYK) in repeated regions of tau microtubule-binding domains, how the primary sequence of adjacent repeats intrinsically influences aggregation and prion-like propagation remains unclear. This study systematically characterized three unmodified, physiologically relevant tau peptide constructs-R1R3, R2R3, and R3R4-to define their intrinsic aggregation kinetics, structural features, and prion-like seeding activity. Among these constructs, we found that R2R3 showed rapid aggregation, distinct β-sheet formation, and potent seeding capable of sustained secondary propagation in cellular biosensor assays. Whereas recent studies have highlighted chemically modified peptides (e.g., acetylated and phosphomimic peptides), our study emphasizes the importance of native, unmodified sequences as fundamental determinants in tau aggregation. Furthermore, these findings establish R2R3 as a robust minimal tau model, providing a valuable tool for mechanistic research and therapeutic screening in tau-related neurodegeneration.

• MeSH
• kinetika MeSH
• lidé MeSH
• proteinové agregáty * MeSH
• proteiny tau * chemie   metabolismus   MeSH
• sekvence aminokyselin MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• proteinové agregáty * MeSH
• proteiny tau * MeSH

The kinetic properties of four columns packed with fully porous particles and three with superficially porous particles were characterized for possible application in proteomic bottom-up analyses. All columns provided an attachment of hydrophobic C18 chains at the surface of the stationary phase. However, they differed in the additional attachment of polar groups and/or endcapping procedure. We have used the retention modeling protocol to explore the separation efficiency and maximal achievable peak capacity on tested columns. Almost all columns provided comparable maximal peak capacity in the range of 500 - 700 for the eight-hour gradient run. This confirms that the family of the stationary phases used in the bottom-up proteomics can be extended. In the case of fully porous particles, we found that the higher the column peak capacity, the higher the number of identified peptides in the simple proteomic sample, with approximately one identified peptide per peak capacity unit. On the contrary, in the case of the superficially porous particles, the number of identified peptides in the sample decreased with the higher column peak capacity. This trend can be overturned only when the lower amount of the sample is injected. Hence, when bottom-up proteomics is considered, the lower loadability of the superficially porous particles still needs to be addressed. Most stationary phases tested can be successfully used in the bottom-up analyses. However, the stationary phases with incorporated polar functional groups reduced the undesirable contribution of free silanol groups to peptide peak tailing and increased the information provided by LC-MS analysis.

• Klíčová slova
• Bottom-up, Column characterization, Gradient elution, Peptide, Proteomics, Reversed-phase retention,
• MeSH
• chromatografie kapalinová metody   přístrojové vybavení   MeSH
• hydrofobní a hydrofilní interakce MeSH
• kinetika MeSH
• peptidy analýza   chemie   MeSH
• poréznost MeSH
• povrchové vlastnosti MeSH
• proteomika * metody   přístrojové vybavení   MeSH
• velikost částic MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• peptidy MeSH

Despite being present in many drugs, guanylhydrazones and semicarbazones are two functional groups that have been little investigated as potential therapeutic strategies for the treatment of Alzheimer's disease (AD). For this reason, we initiated the synthesis and evaluation of these compounds as potential anticholinesterase agents, aiming to offer new alternatives for drug development against AD. In the severe phase of AD butyrylcholinesterase (BChE) becomes the main enzyme responsible for the hydrolysis of acetylcholine (ACh). Therefore, in this project, we present the results of BChE inhibitory activity, enzyme kinetics, cytotoxicity, and molecular modeling studies for three guanylhydrazone and two semicarbazone derivatives that were previously synthesized and evaluated as acetylcholinesterase (AChE) inhibitors. Among the compounds tested, guanylhydrazones (1, 2, and 3) showed inhibitory activity against BChE, exhibiting a mixed non-competitive inhibition profile. Specifically, compound 2 (phenanthrenequinone) demonstrated superior inhibitory potency with an IC50 of 0.68 μM, compared to compound 1 (acridinone) with an IC50 of 3.87 μM, and compound 3 (benzodioxole) with an IC50 of 101.7 μM. In contrast, semicarbazones (4 and 5) showed no BChE inhibition up to the highest concentration tested (300 μM). Importantly, all five compounds were found to be non-cytotoxic. Our results suggest that these compounds have potential as drug prototypes targeting different phases of AD. Compounds 3, 4, and 5 may be more effective in the early phase, when AChE activity remains high; compound 1 could be useful in the intermediate phase; and compound 2 appears particularly promising for the severe phase, when BChE plays a more dominant role.

• Klíčová slova
• Alzheimer's disease, Butyrylcholinesterase, Guanylhydrazones, N9 microglial cell line, Semicarbazones,
• MeSH
• acetylcholinesterasa metabolismus   chemie   MeSH
• Alzheimerova nemoc * farmakoterapie   MeSH
• butyrylcholinesterasa metabolismus   chemie   MeSH
• cholinesterasové inhibitory * chemie   farmakologie   metabolismus   terapeutické užití   chemická syntéza   MeSH
• hydrazony * chemie   farmakologie   MeSH
• kinetika MeSH
• lidé MeSH
• molekulární modely MeSH
• racionální návrh léčiv * MeSH
• semikarbazony * chemie   farmakologie   metabolismus   MeSH
• simulace molekulového dockingu MeSH
• vztahy mezi strukturou a aktivitou MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• acetylcholinesterasa MeSH
• butyrylcholinesterasa MeSH
• cholinesterasové inhibitory * MeSH
• hydrazony * MeSH
• semikarbazony * MeSH

A copper(II) tetrapyrazole-based complex of the composition of [Cu(tpyr)(H2O)(ONO2)]NO3 (1), where tpyr represents a tetradentate N-donor ligand formed by the condensation of 1H-pyrazole-5-carbaldehyde in NaOH/MeOH medium, has been prepared and characterized by elemental analysis, infrared spectroscopy, ultraviolet-visible spectroscopy, mass spectrometry, electron paramagnetic resonance and single-crystal X-ray diffraction. Spectrophotometric measurements demonstrated a remarkable peroxidase activity of the complex, which utilized hydrogen peroxide for the oxidation of phenolic compounds such as guaiacol or 3,5-dichloro-2-hydroxybenzene sulfonic acid. The optimum conditions for this reaction were found at pH 8 in ammonium bicarbonate buffer, although the activity was low but still detectable at pH 5-6 in ammonium acetate. As a peroxidase mimic, the complex exhibited enzyme-like Michaelis-Menten kinetics, showing a hyperbolic dependence of the reaction rate on hydrogen peroxide concentration. The determined Km and kcat values were 651 μmol·l-1 and 6.7 × 10-4 s-1, respectively, compared to 41 μmol·l-1 and 73 s-1 for horseradish peroxidase. EPR spectroscopy of the reaction mixture revealed no change in the copper (II) oxidation state during catalysis, suggesting that the oxidation of guaiacol may occur simultaneously with the reduction of hydrogen peroxide to water at the copper centre.

• Klíčová slova
• Copper(II), Crystal structure, MALDI-TOF, Peroxidase activity, Tetrapyrazole, XPS,
• MeSH
• biomimetické materiály * chemie   MeSH
• kinetika MeSH
• komplexní sloučeniny * chemie   chemická syntéza   MeSH
• krystalografie rentgenová MeSH
• měď * chemie   MeSH
• oxidace-redukce MeSH
• peroxid vodíku chemie   MeSH
• peroxidasa * chemie   MeSH
• pyrazoly * chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• komplexní sloučeniny * MeSH
• měď * MeSH
• peroxid vodíku MeSH
• peroxidasa * MeSH
• pyrazoly * MeSH

The widespread use of synthetic polymers since the mid-twentieth century has led to significant environmental pollution from microplastics (MPs). These MPs, which persist in ecosystems, can interact with various pollutants, including pesticides such as tebuconazole (TEB). The subject paper investigates the sorption behaviour of TEB on different types of MPs (polystyrene, polypropylene, and polyamide-6), focusing on the kinetics and isotherms of these interactions. The role of metal cations (Al, Cd, Cu, Pb, Zn) in influencing TEB sorption is also investigated. Our findings highlight critical flaws that invalidate the original article, mainly in the interpretation of TEB physicochemical properties, such as pKa and speciation, and the importance of considering metal ion complexation in environmental risk assessment. The sorption models used by the original authors, although widely used, are questioned for their accuracy in representing real-world scenarios.

• Klíčová slova
• Metal cations, complexation, environmental pollution, metal speciation, pesticide interaction,
• MeSH
• adsorpce MeSH
• chemické látky znečišťující vodu * chemie   MeSH
• chemické modely MeSH
• kinetika MeSH
• mikroplasty * chemie   MeSH
• triazoly * chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• chemické látky znečišťující vodu * MeSH
• mikroplasty * MeSH
• tebuconazole MeSH Prohlížeč
• triazoly * MeSH

Thermokinetic characterization of amorphous carbamazepine was performed utilizing non-isothermal differential scanning calorimetry (DSC) and thermogravimetry (TGA). Structural relaxation of the amorphous matrix was described in terms of the Tool-Narayanaswamy-Moynihan model with the following parameters: Δh* ≈ 200-300 kJ·mol-1, β = 0.57, x = 0.44. The crystallization of the amorphous phase was modeled using complex Šesták-Berggren kinetics, which incorporates temperature-dependent activation energy and degree of autocatalysis. The activation energy of the crystal growth was determined to be >320 kJ·mol-1 at the glass transition temperature (Tg). Owing to such a high value, the amorphous carbamazepine is stable at Tg, allowing for extensive processing of the amorphous phase (e.g., self-healing of the quench-induced mechanical defects or internal stress). A discussion was conducted regarding the converse relation between the activation energies of relaxation and crystal growth, which is possibly responsible for the absence of sub-Tg crystal growth modes. The high-temperature thermal decomposition of carbamazepine proceeds via multistep kinetics, identically in both an inert and an oxidizing atmosphere. A complex reaction mechanism, consisting of a series of consecutive and competing reactions, was proposed to explain the second decomposition step, which exhibited a temporary mass increase. Whereas a negligible degree of carbamazepine degradation was predicted for the temperature characteristic of the pharmaceutical hot-melt extrusion (~150 °C), the degradation risk during the pharmaceutical 3D printing was calculated to be considerably higher (1-2% mass loss at temperatures 190-200 °C).

• Klíčová slova
• carbamazepine, crystal growth, structural relaxation, thermal decomposition,
• MeSH
• diferenciální skenovací kalorimetrie MeSH
• karbamazepin * chemie   MeSH
• kinetika MeSH
• krystalizace MeSH
• teplota MeSH
• termogravimetrie MeSH
• tranzitní teplota MeSH
• vysoká teplota MeSH
• změna skupenství * MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• karbamazepin * MeSH

The inactivation of sixteen dairy phages was tested as a function of time in a laboratory scale reactor, under near UV-C radiation (λ = 254 nm). Unlike previous studies focusing on liquid suspensions, this work specifically examines phage inactivation on dry surfaces, mimicking industrial environments where bioaerosols and contaminated surfaces contribute to phage dissemination. Moreover, most of the tested phages were isolated in our country and have not been studied using this technology yet. Phage suspensions (106-107 PFU/mL) were deposited on borosilicate glass plates, dried and exposed to increasing UV-C doses. No infective phage particles were detected for six phages when treated with a dose of 0.13 J/cm2, while the remaining ten exhibited titer reductions between 3.16 and 4.45 log orders when treated with doses of 0.13 or 0.32 J/cm2. These dose values are feasible to apply in the industry, since short treatment times and few lamps are required, which implies a low investment and maintenance cost. For higher doses, a tailing effect was evidenced for the 10 phages. This behavior was also demonstrated in a second cycle of treatment under UV-C radiation for phages MLC-A and LDG. To quantify and predict phage inactivation, eight kinetic models were applied, with the Geeraerd and Baranyi and Roberts models providing the best fit (RMSE: 6.86 × 10-6 - 3.54 %). These findings offer valuable insights into phage control strategies for the dairy industry, improving current sanitation protocols and contributing to the development of effective UV-C disinfection guidelines for food processing environments.

• Klíčová slova
• Bacteriophage, Dairy, Dose, Germicidal radiation, Inactivation kinetic model,
• MeSH
• bakteriofágy * účinky záření   fyziologie   MeSH
• dezinfekce * metody   MeSH
• inaktivace viru * účinky záření   MeSH
• kinetika MeSH
• mlékárenství MeSH
• ultrafialové záření * MeSH
• Publikační typ
• časopisecké články MeSH

Determining why convergent traits use distinct versus shared genetic components is crucial for understanding how evolutionary processes generate and sustain biodiversity. However, the factors dictating the genetic underpinnings of convergent traits remain incompletely understood. Here, we use heterologous protein expression, biochemical assays, and phylogenetic analyses to confirm the origin of a luciferase gene from haloalkane dehalogenases in the brittle star Amphiura filiformis. Through database searches and gene tree analyses, we also show a complex pattern of the presence and absence of haloalkane dehalogenases across organismal genomes. These results first confirm parallel evolution across a vast phylogenetic distance, because octocorals like Renilla also use luciferase derived from haloalkane dehalogenases. This parallel evolution is surprising, even though previously hypothesized, because many organisms that also use coelenterazine as the bioluminescence substrate evolved completely distinct luciferases. The inability to detect haloalkane dehalogenases in the genomes of several bioluminescent groups suggests that the distribution of this gene family influences its recruitment as a luciferase. Together, our findings highlight how biochemical function and genomic availability help determine whether distinct or shared genetic components are used during the convergent evolution of traits like bioluminescence.

• Klíčová slova
• bioluminescence, convergent evolution, haloalkane dehalogenase, luciferase, parallel evolution,
• MeSH
• biokatalýza MeSH
• Echinodermata * genetika   metabolismus   MeSH
• fylogeneze MeSH
• genom * MeSH
• genomika MeSH
• hydrolasy * genetika   metabolismus   MeSH
• kinetika MeSH
• luciferasy * genetika   metabolismus   MeSH
• molekulární evoluce * MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• haloalkane dehalogenase MeSH Prohlížeč
• hydrolasy * MeSH
• luciferasy * MeSH