oxygen-binding properties
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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
High-performance fibre-reinforced polymer composites are important construction materials based not only on the specific properties of the reinforcing fibres and the flexible polymer matrix but also on the compatible properties of the composite interphase. First, oxygen-free (a-CSi:H) and oxygen-binding (a-CSiO:H) plasma nanocoatings of different mechanical and tribological properties were deposited on planar silicon dioxide substrates that closely mimic E-glass. The nanoscratch test was used to characterize the nanocoating adhesion expressed in terms of critical normal load and work of adhesion. Next, the same nanocoatings were deposited on E-glass fibres, which were used as reinforcements in the polyester composite to affect its interphase properties. The shear properties of the polymer composite were characterized by macro- and micromechanical tests, namely a short beam shear test to determine the short-beam strength and a single fibre push-out test to determine the interfacial shear strength. The results of the polymer composites showed a strong correlation between the short-beam strength and the interfacial shear strength, proving that both tests are sensitive to changes in fibre-matrix adhesion due to different surface modifications of glass fibres (GF). Finally, a strong correlation between the shear properties of the GF/polyester composite and the adhesion of the plasma nanocoating expressed through the work of adhesion was demonstrated. Thus, increasing the work of adhesion of plasma nanocoatings from 0.8 to 1.5 mJ·m-2 increased the short-beam strength from 23.1 to 45.2 MPa. The results confirmed that the work of adhesion is a more suitable parameter in characterising the level of nanocoating adhesion in comparison with the critical normal load.
- Klíčová slova
- glass fibre, interfacial shear strength, mechanical properties, plasma nanocoatings, polymer composite, short-beam strength, work of adhesion,
- Publikační typ
- časopisecké články MeSH
Carbon nanotubes (CNT) are one of the most promising nanomaterials for use in medicine. The blood biocompatibility of CNT is a critical safety issue. In the bloodstream, proteins bind to CNT through non-covalent interactions to form a protein corona, thereby largely defining the biological properties of the CNT. Here, we characterize the interactions of carboxylated-multiwalled carbon nanotubes (CNTCOOH) with common human proteins and investigate the effect of the different protein coronas on the interaction of CNTCOOH with human blood platelets (PLT). Molecular modeling and different photophysical techniques were employed to characterize the binding of albumin (HSA), fibrinogen (FBG), γ-globulins (IgG) and histone H1 (H1) on CNTCOOH. We found that the identity of protein forming the corona greatly affects the outcome of CNTCOOH's interaction with blood PLT. Bare CNTCOOH-induced PLT aggregation and the release of platelet membrane microparticles (PMP). HSA corona attenuated the PLT aggregating activity of CNTCOOH, while FBG caused the agglomeration of CNTCOOH nanomaterial, thereby diminishing the effect of CNTCOOH on PLT. In contrast, the IgG corona caused PLT fragmentation, and the H1 corona induced a strong PLT aggregation, thus potentiating the release of PMP.
- Klíčová slova
- Biocompatibility, Carbon nanotubes, Nanoparticles, Nanotoxicity, Platelets, Protein corona,
- MeSH
- aktivace trombocytů MeSH
- cirkulární dichroismus MeSH
- krevní proteiny chemie metabolismus MeSH
- L-laktátdehydrogenasa metabolismus MeSH
- lidé MeSH
- molekulární modely MeSH
- nanotrubičky uhlíkové chemie ultrastruktura MeSH
- povrchové vlastnosti MeSH
- proteom metabolismus MeSH
- reaktivní formy kyslíku metabolismus MeSH
- skot MeSH
- trombocyty metabolismus ultrastruktura MeSH
- vazba proteinů MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- skot MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- krevní proteiny MeSH
- L-laktátdehydrogenasa MeSH
- nanotrubičky uhlíkové MeSH
- proteom MeSH
- reaktivní formy kyslíku MeSH
Hemoglobin is an oxygen-transport protein in red blood cells that interacts with multiple ligands, e.g., oxygen, carbon dioxide, carbon monoxide, and nitric oxide. Genetic variations in hemoglobin chains, such as those underlying sickle cell disease and thalassemias, present substantial clinical challenges. Here, we review the progress in research, including the use of allosteric modulators, pharmacological chaperones, and antioxidant treatments, which has begun to improve hemoglobin stability and oxygen affinity. According to UniProt (as of 7 August 2024), 819 variants of the α-hemoglobin subunit and 771 variants of the β-hemoglobin subunit have been documented, with over 116 classified as unstable. These data demonstrate the urgent need to develop variant-specific stabilizing options. Beyond small-molecule drugs/binders, novel protein-based strategies-such as engineered hemoglobin-binding proteins (including falcilysin, llama-derived nanobodies, and α-hemoglobin-stabilizing proteins)-offer promising new options. As our understanding of hemoglobin's structural and functional diversity grows, so does the potential for genotype-driven approaches. Continued research into hemoglobin stabilization and ligand-binding modification may yield more precise, effective treatments and pave the way toward effective strategies for hemoglobinopathies.
- Klíčová slova
- 2,3-bisphosphoglycerate (2,3-BPG), Bohr effect, allosteric regulation, genetic variants, hemoglobin (Hb), oxygen affinity, oxygen-binding properties, protein engineering, sickle cell disease (SCD), thalassemia,
- MeSH
- hemoglobinopatie farmakoterapie genetika metabolismus MeSH
- hemoglobiny * genetika chemie metabolismus MeSH
- lidé MeSH
- stabilita proteinů účinky léků MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
- Názvy látek
- hemoglobiny * MeSH
We analyzed antibacterial effects of several novel phthalocyanines against Escherichia coli and evaluated the suitability of flow cytometry for the detection of antibacterial effects of phthalocyanines in comparison with routinely used cultivation. After 3h of exposure under cool white light eight cationic phthalocyanines showed very high antibacterial activity in the concentration of 2.00 mg L(-1) and four of them were even efficient in the concentration of 0.20 mg L(-1). Antibacterial activity of neutral and anionic compounds was considerably lower or even negligible. No antibacterial effect was detected when bacteria were exposed without illumination. Binding affinity to bacterial cells was found to represent an important parameter influencing phthalocyanine antibacterial activity that can be modified by total charge of peripheral substituents and by the presence of suitable functional groups inside them. Agglomeration of cells observed in suspensions treated with a higher concentration of certain cationic phthalocyanines (the strongest binders to bacterial membrane) affected cytometric measurements of total cell counts, thus without appropriate pretreatment of the sample before analysis this parameter seems not to be fully valid in the evaluation of phthalocyanine antibacterial activity. Cytometric measurement of cell membrane integrity appears to be a suitable and even more sensitive parameter than cultivation.
- Klíčová slova
- Antibacterial effect, Binding affinity, Cell membrane integrity, Cultivation techniques, Flow cytometry, Photosensitizers, Phthalocyanines, Singlet oxygen,
- MeSH
- antibakteriální látky chemie farmakologie MeSH
- Escherichia coli účinky léků MeSH
- fotosenzibilizující látky chemie farmakologie MeSH
- indoly chemie farmakologie MeSH
- isoindoly MeSH
- průtoková cytometrie MeSH
- singletový kyslík metabolismus MeSH
- světlo MeSH
- Publikační typ
- časopisecké články MeSH
- hodnotící studie MeSH
- práce podpořená grantem MeSH
- Názvy látek
- antibakteriální látky MeSH
- fotosenzibilizující látky MeSH
- indoly MeSH
- isoindoly MeSH
- phthalocyanine MeSH Prohlížeč
- singletový kyslík MeSH
The surface and the "bulk" structure of TiNi implants were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoemission spectroscopy (XPS), and scanning Auger microprobe analysis (AES). TiNi implants were compared with otherwise identically prepared non-implanted specimens, and sputter-cleaned and reoxidized samples. Non-implanted and implanted samples had essentially the same surface topography and microstructure. Ti, O, and C were the dominant elements detected on the surface. Trace amounts (approximately 1 at%) of Ni and Ca, N, Si, B, and S were also detected. Ti was present as TiO2 on the surface, while nickel was present in metallic form. A significant difference in Ni peak intensity was observed when retrieved or non-implanted control samples (a very low nickel content) were compared with sputter-cleaned and reoxidized samples (well-detected nickel). It is evident that the method of passivation is crucial for nickel loosening. No major changes occurred in the TiNi samples bulk structure or in the surface oxide during the implantation periods investigated.
- MeSH
- biokompatibilní materiály chemie MeSH
- elektronová mikroskopie MeSH
- kobalt chemie MeSH
- kolagen metabolismus MeSH
- kyslík metabolismus MeSH
- lidé MeSH
- mikroskopie elektronová rastrovací MeSH
- nikl chemie MeSH
- osteotomie přístrojové vybavení MeSH
- povrchové vlastnosti MeSH
- testování materiálů MeSH
- titan chemie MeSH
- vazba proteinů MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- biokompatibilní materiály MeSH
- kobalt MeSH
- kolagen MeSH
- kyslík MeSH
- nikl MeSH
- titan MeSH
- titanium-nickel-cobalt alloy MeSH Prohlížeč
We prepared a series of cryptogein mutants, an elicitor from Phytophthora cryptogea, with altered abilities to bind sterols and fatty acids. The induction of the early events, i.e., synthesis of active oxygen species and pH changes, in suspension tobacco cells by these mutated proteins was proportional to their ability to bind sterols but not fatty acids. Although the cryptogein-sterol complex was suggested to be a form triggering a defense reaction in tobacco, some proteins unable to bind sterols induced the synthesis of active oxygen species and pH changes. The modeling experiments showed that conformational changes after the introduction of bulky residues into the omega loop of cryptogein resemble those induced by sterol binding. These changes may be necessary for the ability to trigger the early events by elicitins. However, the ability to stimulate necrosis in suspension tobacco cells and the expression of defense proteins in tobacco plants were linked neither to the lipid binding capacity nor to the capacity to provoke the early events. On the basis of these experiments and previous results, we propose that elicitins could stimulate two signal pathways. The first one induces necroses and the expression of pathogen-related proteins, includes tyrosine protein kinases and mitogen-activated protein kinases, and depends on the overall structure and charge distribution. The second type of interaction is mediated by phospholipase C and protein kinase C. It triggers the synthesis of active oxygen species and pH changes. This interaction depends on the ability of elicitins to bind sterols.
- MeSH
- bílkoviny řas chemická syntéza genetika metabolismus toxicita MeSH
- cirkulární dichroismus MeSH
- ergosterol analogy a deriváty metabolismus MeSH
- fenylalaninamoniaklyasa biosyntéza MeSH
- fungální proteiny MeSH
- kvantitativní vztahy mezi strukturou a aktivitou MeSH
- mastné kyseliny metabolismus MeSH
- metabolismus lipidů MeSH
- mutageneze cílená * MeSH
- mykotoxiny chemická syntéza genetika toxicita MeSH
- NADPH-oxidasy biosyntéza MeSH
- nemoci rostlin mikrobiologie MeSH
- Phytophthora genetika patogenita MeSH
- počítačová simulace MeSH
- proteiny MeSH
- reaktivní formy kyslíku metabolismus MeSH
- rekombinantní proteiny chemická syntéza genetika toxicita MeSH
- rostlinné proteiny biosyntéza MeSH
- tabák cytologie enzymologie metabolismus mikrobiologie MeSH
- vazba proteinů genetika MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- bílkoviny řas MeSH
- cryptogein protein, Phytophthora cryptogea MeSH Prohlížeč
- dehydroergosterol MeSH Prohlížeč
- elicitin, Phytophthora MeSH Prohlížeč
- ergosterol MeSH
- fenylalaninamoniaklyasa MeSH
- fungální proteiny MeSH
- mastné kyseliny MeSH
- mykotoxiny MeSH
- NADPH-oxidasy MeSH
- pathogenesis-related proteins, plant MeSH Prohlížeč
- proteiny MeSH
- reaktivní formy kyslíku MeSH
- rekombinantní proteiny MeSH
- rostlinné proteiny MeSH
Phthalocyanines are promising photosensitizers for use in various branches of science including nanotechnology. In the presence of visible light and diatomic oxygen, phthalocyanines can react to produce singlet oxygen (1O2*), which has known inhibitory effects on cellular growth and metabolic activity, although other mechanisms may be involved. The present work focuses on the properties of phthalocyanines (atom charge densities, singlet oxygen production, inhibition effects at various irradiances) contributing to toxicity against the cyanobacteria, Synechococcus nidulans. Our results indicate that positive charge densities at peripheral parts of substituents exhibit greater inhibitory effects against S. nidulans than the amount of singlet oxygen produced, potentially by binding to negatively charged membranes on the cell surface. The weak effect of 1O2* was further demonstrated by a 10% increase in phthalocyanine toxicity (the maximal inhibition detected) when the irradiance increased 3-fold from 1200 to 4000 lux.
- MeSH
- indoly chemie toxicita MeSH
- isoindoly MeSH
- radiosenzibilizující látky chemie toxicita MeSH
- singletový kyslík metabolismus MeSH
- sinice účinky léků růst a vývoj MeSH
- světlo MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- indoly MeSH
- isoindoly MeSH
- phthalocyanine MeSH Prohlížeč
- radiosenzibilizující látky MeSH
- singletový kyslík MeSH
Insulin is a peptide responsible for regulating the metabolic homeostasis of the organism; it elicits its effects through binding to the transmembrane insulin receptor (IR). Insulin mimetics with agonistic or antagonistic effects toward the receptor are an exciting field of research and could find applications in treating diabetes or malignant diseases. We prepared five variants of a previously reported 20-amino acid insulin-mimicking peptide. These peptides differ from each other by the structure of the covalent bridge connecting positions 11 and 18. In addition to the peptide with a disulfide bridge, a derivative with a dicarba bridge and three derivatives with a 1,2,3-triazole differing from each other by the presence of sulfur or oxygen in their staples were prepared. The strongest binding to IR was exhibited by the peptide with a disulfide bridge. All other derivatives only weakly bound to IR, and a relationship between increasing bridge length and lower binding affinity can be inferred. Despite their nanomolar affinities, none of the prepared peptide mimetics was able to activate the insulin receptor even at high concentrations, but all mimetics were able to inhibit insulin-induced receptor activation. However, the receptor remained approximately 30% active even at the highest concentration of the agents; thus, the agents behave as partial antagonists. An interesting observation is that these mimetic peptides do not antagonize insulin action in proportion to their binding affinities. The compounds characterized in this study show that it is possible to modulate the functional properties of insulin receptor peptide ligands using disulfide mimetics.
- Klíčová slova
- antagonism, dicarba, disulfide mimetics, insulin mimetic peptide, insulin receptor, staple, triazole,
- MeSH
- disulfidy chemie MeSH
- inzulin * metabolismus MeSH
- peptidy chemie MeSH
- receptor inzulinu * MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- disulfidy MeSH
- inzulin * MeSH
- peptidy MeSH
- receptor inzulinu * MeSH
Densely packed ZnO nanocolumns (NCs), perpendicularly oriented to the fused-silica substrates were directly grown under hydrothermal conditions at 90 °C, with a growth rate of around 0.2 μm/h. The morphology of the nanostructures was visualized and analyzed by scanning electron microscopy (SEM). The surface properties of ZnO NCs and the binding state of present elements were investigated before and after different plasma treatments, typically used in plasma-enhanced CVD solar cell deposition processes, by X-ray photoelectron spectroscopy (XPS). Photothermal deflection spectroscopy (PDS) was used to investigate the optical and photoelectrical characteristics of the ZnO NCs, and the changes induced to the absorptance by the plasma treatments. A strong impact of hydrogen plasma treatment on the free-carrier and defect absorption of ZnO NCs has been directly detected in the PDS spectra. Although oxygen plasma treatment was proven to be more efficient in the surface activation of the ZnO NC, the PDS analysis showed that the plasma treatment left the optical and photoelectrical features of the ZnO NCs intact. Thus, it was proven that the selected oxygen plasma treatment can be of great benefit for the development of thin film solar cells based on ZnO NCs.
