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.
- MeSH
- Azotobacter vinelandii enzymology MeSH
- Bordetella pertussis enzymology MeSH
- Chemotaxis MeSH
- Escherichia coli enzymology MeSH
- Globins chemistry MeSH
- Heme chemistry MeSH
- Hemoglobins chemistry MeSH
- Catalytic Domain MeSH
- Catalysis MeSH
- Oxygen chemistry MeSH
- Phosphorus-Oxygen Lyases chemistry MeSH
- Evolution, Molecular MeSH
- Molecular Sequence Data MeSH
- Myoglobin chemistry MeSH
- Protein Kinases chemistry MeSH
- Escherichia coli Proteins chemistry MeSH
- Gene Expression Regulation, Enzymologic * MeSH
- Amino Acid Sequence MeSH
- Sequence Homology, Amino Acid MeSH
- Protein Binding MeSH
- Binding Sites MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Review 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.
- MeSH
- Platelet Activation MeSH
- Circular Dichroism MeSH
- Blood Proteins chemistry metabolism MeSH
- L-Lactate Dehydrogenase metabolism MeSH
- Humans MeSH
- Models, Molecular MeSH
- Nanotubes, Carbon chemistry ultrastructure MeSH
- Surface Properties MeSH
- Proteome metabolism MeSH
- Reactive Oxygen Species metabolism MeSH
- Cattle MeSH
- Blood Platelets metabolism ultrastructure MeSH
- Protein Binding MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Cattle MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't 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.
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.
- MeSH
- Disulfides chemistry MeSH
- Insulin * metabolism MeSH
- Peptides chemistry MeSH
- Receptor, Insulin * MeSH
- Publication type
- Journal Article MeSH
The formation of self-assemblies between CdSe quantum dots (QDs) and Zn phthalocyanines (Pc) and azaphthalocyanines (AzaPc) bearing alkylsulfanyl substituents and the photophysical properties of these assemblies were studied using both steady-state and time-resolved luminescence/absorption spectroscopy. The formation of the self-assemblies was accompanied by a blue shift of the Q band of the dyes and by a quenching of the CdSe QDs luminescence. The largest spectral shift of the Q-band was approximately 7 nm and was observed for pentan-3-ylsulfanyl-functionalised phthalocyanine (). Assuming a 1 : 1 stoichiometry, the calculated binding constant was 4 × 10(4) M(-1). Pc substituted with the bulky tert-butylsulfanyl groups (1) exhibited a smaller shift of the Q band. The quenching of the CdSe QDs luminescence by 1 was more effective than that observed for 3. The results indicated that the luminescence quenching may be due to a photoinduced charge transfer between 1 or 3 and the CdSe QDs. In contrast, the AzaPc (2) with the same substituents as 1 had little effect on the QDs luminescence. For all cases, we found an inefficient resonance energy transfer between the attached dyes and the CdSe QD. The formation of the self-assemblies had negligible effects on the photogeneration of the singlet oxygen, O2((1)Δg), that was fully controlled only by the absorption of the light by the macrocycles.
- MeSH
- Spectrometry, Fluorescence MeSH
- Indoles chemistry MeSH
- Quantum Theory MeSH
- Quantum Dots * MeSH
- Organometallic Compounds chemistry MeSH
- Solvents chemistry MeSH
- Cadmium Compounds chemistry MeSH
- Selenium Compounds chemistry MeSH
- Particle Size MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Quaternary benzo[c]phenanthridine alkaloids (QBAs) are natural products isolated from plants of Fumariaceae, Papaveraceae, Ranunculaceae and Rutaceae families. They are intensively studied for their biological activities, but they have also attractive fluorescence properties. Chromophores responsible for fluorescence are fused aromatic ring systems with electron-donor groups containing oxygen (OH, OCH3, OCH2O). Recently we have described fluorescent characteristics of QBAs - macarpine (MA), sanguirubine (SR), chelirubine (CHR), sanguilutine (SL), chelilutine (CHL), sanguinarine (SA) and chelerythrine (CHE) - on interaction with living cells. All these alkaloids immediately enter the living cells and MA-, CHRand SA-bound DNA; they showed a nucleus architecture similar to common DNA dyes. Moreover, MA binds to DNA stoichiometrically and can rapidly report the cellular DNA content in living cells at a resolution adequate for cell cycle analysis. QBAs could be excited by common argon lasers (488 nm) emitting light in the 575-755 nm range. Spectral characteristics of MA allow simultaneous surface immunophenotyping. These characteristics allow multiple applications of the above-mentioned QBAs with significant diagnostic utility. They can be used as supravital fluorescent DNA probes both in fluorescence microscopy and flow cytometry including multiparameter analysis.
AIMS: The diverse physiological functions of histamine are mediated through distinct histamine receptors. In this study we investigated the role of H2R and H4R in the effects of histamine on the production of reactive oxygen species by phagocytes in whole blood. MAIN METHODS: Changes in reactive oxygen species (ROS) production by whole blood phagocytes after treatment with histamine, H4R agonists (4-methylhistamine, VUF8430), H2R agonist (dimaprit) and their combinations with H4R antagonist (JNJ10191584) and H2R antagonist (ranitidine) were determined using the chemiluminescence (CL) assay. To exclude the direct scavenging effects of the studied compounds on the CL response, the antioxidant properties of all compounds were measured using several methods (TRAP, ORAC, and luminol-HRP-H2O2 based CL). KEY FINDINGS: Histamine, 4-methylhistamine, VUF8430 and dimaprit inhibited the spontaneous and OZP-activated whole blood CL in a dose-dependent manner. On the other hand, only VUF8430 was able to inhibit PMA-activated whole blood CL. Ranitidine, but not JNJ10191584, completely reduced the effects of histamine, 4-methylhistamine and dimaprit. The direct scavenging ability of tested compounds was negligible. SIGNIFICANCE: Our results demonstrate that the inhibitory effects of histamine on ROS production in whole blood phagocytes were caused by H2R. Our results also suggest that H4R agonists in concentrations higher than 10(-6)M may also influence ROS production via binding to H2R.
- MeSH
- Histamine Agonists pharmacology MeSH
- Benzimidazoles pharmacology MeSH
- Dimaprit pharmacology MeSH
- Phagocytes drug effects metabolism MeSH
- Guanidines pharmacology MeSH
- Histamine physiology MeSH
- Humans MeSH
- Methylhistamines pharmacology MeSH
- Reactive Oxygen Species blood MeSH
- Receptors, Histamine H2 metabolism MeSH
- Receptors, Histamine metabolism MeSH
- Receptors, G-Protein-Coupled agonists metabolism MeSH
- Thiourea analogs & derivatives pharmacology MeSH
- Check Tag
- Humans MeSH
- Male MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Free cellular iron catalyzes the formation of toxic hydroxyl radicals and therefore chelation of iron could be a promising therapeutic approach in pathological states associated with oxidative stress. Salicylaldehyde isonicotinoyl hydrazone (SIH) is a strong intracellular iron chelator with well documented potential to protect against oxidative damage both in vitro and in vivo. Due to the short biological half-life of SIH and risk of toxicity due to iron depletion, boronate prochelator BSIH has been designed. BSIH cannot bind iron until it is activated by certain reactive oxygen species to active chelator SIH. The aim of this study was to examine the toxicity and cytoprotective potential of BSIH, SIH, and their decomposition products against hydrogen peroxide-induced injury of H9c2 cardiomyoblast cells. Using HPLC, we observed that salicylaldehyde was the main decomposition products of SIH and BSIH, although a small amount of salicylic acid was also detected. In the case of BSIH, the concentration of formed salicylaldehyde consistently exceeded that of SIH. Isoniazid and salicylic acid were not toxic nor did they provide any antioxidant protective effect in H9c2 cells. In contrast, salicylaldehyde was able to chelate intracellular iron and significantly preserve cellular viability and mitochondrial inner membrane potential induced by hydrogen peroxide. However it was consistently less effective than SIH. The inherent toxicities of salicylaldehyde and SIH were similar. Hence, although SIH - the active chelating agent formed following the BSIH activation - undergoes rapid hydrolysis, its principal decomposition product salicylaldehyde accounts markedly for both cytoprotective and toxic properties.
- MeSH
- Aldehydes pharmacology toxicity MeSH
- Cell Line MeSH
- Iron Chelating Agents pharmacology toxicity MeSH
- Hydrazones pharmacology toxicity MeSH
- Rats MeSH
- Boronic Acids pharmacology toxicity MeSH
- Isonicotinic Acids pharmacology toxicity MeSH
- Membrane Potential, Mitochondrial drug effects MeSH
- Myoblasts, Cardiac drug effects metabolism MeSH
- Oxidative Stress drug effects MeSH
- Hydrogen Peroxide toxicity MeSH
- Half-Life MeSH
- Reactive Oxygen Species metabolism MeSH
- Cell Survival drug effects MeSH
- Chromatography, High Pressure Liquid MeSH
- Iron metabolism MeSH
- Animals MeSH
- Check Tag
- Rats MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
BACKGROUND/AIMS: Melatonin is a hormone transferring information about duration of darkness to the organism and is known to modulate several signaling pathways in the cells, e.g. generation of endoplasmic reticulum stress, oxidative status of the cells, etc. Melatonin has been shown to exert antiproliferative and cytotoxic effects on various human cancers. We proposed that this hormone can differently affect tumour cells and healthy cells. METHODS: We compared the effect of 24 h melatonin treatment on calcium transport (by fluorescent probes FLUO-3AM and Rhod-5N), ER stress (determined as changes in the expression of CHOP, XBP1 and fluorescently, using Thioflavin T), ROS formation (by CellROX® Green/Orange Reagent) and apoptosis induction (by Annexin-V-FLUOS/propidiumiodide) in two tumour cell lines - ovarian cancer cell line A2780 and stable cell line DLD1 derived from colorectal carcinoma, with non-tumour endothelial cell line EA.hy926. RESULTS: Melatonin increased apoptosis in both tumour cell lines more than twice, while in EA.hy926 cells the apoptosis was increased only by 30%. As determined by silencing with appropriate siRNAs, both, type 1 sodium/calcium exchanger and type 1 IP3 receptor are involved in the apoptosis induction. Antioxidant properties of melatonin were significantly increased in EA.hy926 cells, while in tumour cell lines this effect was much weaker. CONCLUSION: Taken together, melatonin has different antioxidative effects on tumour cells compared to non-tumour ones; it also differs in the ability to induce apoptosis through the type 1 sodium/calcium exchanger, and type 1 IP3 receptor. Different targeting of calcium transport systems in tumour and normal, non-tumour cells is suggested as a key mechanism how melatonin can exert its anticancer effects. Therefore, it might have a potential as a novel therapeutic implication in cancer treatment.
- MeSH
- Apoptosis drug effects MeSH
- Cytosol metabolism MeSH
- Microscopy, Fluorescence MeSH
- Inositol 1,4,5-Trisphosphate Receptors antagonists & inhibitors genetics MeSH
- Humans MeSH
- RNA, Small Interfering metabolism MeSH
- Melatonin toxicity MeSH
- Cell Line, Tumor MeSH
- Sodium-Calcium Exchanger antagonists & inhibitors genetics metabolism MeSH
- Reactive Oxygen Species metabolism MeSH
- RNA Interference MeSH
- Endoplasmic Reticulum Stress drug effects MeSH
- Transcription Factor CHOP genetics metabolism MeSH
- Calcium metabolism MeSH
- X-Box Binding Protein 1 genetics metabolism MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
