Deamidation of -Asn-Gly- sequences during sample preparation for proteomics: Consequences for MALDI and HPLC-MALDI analysis

We find that peptides containing -Asn-Gly- sequences typically show approximately 70-80% degree of deamidation after standard overnight (approximately 12 h) tryptic digestion at 37 degrees C. This emphasizes the need for more detailed information about the deamidation reaction in -Asn-Gly- sequences, in which two deamidated species are produced, one containing an aspartic acid (-Asp-Gly-) residue and the other containing an isoaspartic acid (-betaAsp-Gly-) residue. For the peptide SLNGEWR (54-60 beta-galactosidase, E. coli), all three components of the reaction mixture were separated by HPLC on C18 300-A sorbent, with trifluoroacetic acid as an ion-pairing modifier. Their intensity ratios suggested the elution order -betaAsp-/-Asn-/-Asp-, which was subsequently confirmed by MALDI MS and MS/MS analysis. The kinetics of the deamidation was studied in detail for the synthetic SLNGEWR parent using RP HPLC with UV detection. The half-life of this peptide was found to be approximately 8 h under digestion conditions. Analysis of a large pool of peptide retention data shows that the -betaAsp-/-Asn-/ -Asp- retention order is normally observed under the above conditions, especially if the original -NG- sequence is surrounded by hydrophobic amino acids. However, changing chromatographic conditions to 100-A pore size sorbents, or using formic acid as a modifier, increases the retention time of -betaAsp- relative to the -Asn-/-Asp- pair, so the order can sometimes be different.     

Intercomparison study of atmospheric mercury models: 2. Modelling results vs. long-term observations and comparison of country deposition budgets

Five regional scale models with a horizontal domain covering the European continent and its surrounding seas, two hemispheric and one global scale model participated in the atmospheric Hg modelling intercomparison study. The models were compared between each other and with available measurements from 11 monitoring stations of the EMEP measurement network. Because only a very limited number of long-term measurement records of Hg were available, significant attention was given to the intercomparison of modelling results. Monthly and annually averaged values of Hg concentrations and depositions as well as items of the Hg deposition budgets for individual European countries were compared. The models demonstrated good agreement (within +/-20%) between annual modelled and observed values of gaseous elemental Hg. Modelled values of Hg wet deposition in Western and Central Europe agreed with the observations within +/-45%. The probability to predict wet depositions within a factor of 2 with regard to measurements was 50-70% for all the models. The scattering of modelling results for dry depositions of Hg was more significant (up to +/-50% at the annual scale and even higher for monthly data). Contribution of dry deposition to the total Hg deposition was estimated at 20-30% with elevated dry deposition fluxes during summer time. The participating models agree in their predictions of transboundary pollution for individual countries within +/-60% at the monthly scale and within +/-30% at the annual scale. For the cases investigated, all the models predict that the major part of national anthropogenic Hg emissions is transported outside the country territory.     

Magnetic Hyperthermia Nanoarchitectonics via Iron Oxide Nanoparticles Stabilised by Oleic Acid: Anti-Tumour Efficiency and Safety Evaluation in Animals with Transplanted Carcinoma

In this study, we developed iron oxide nanoparticles stabilised with oleic acid/sodium oleate that could exert therapeutic effects for curing tumours via magnetic hyperthermia. A suspension of iron oxide nanoparticles was produced and characterised. The toxicity of the synthesised composition was examined in vivo and found to be negligible. Histological examination showed a low local irritant effect and no effect on the morphology of the internal organs. The efficiency of magnetic hyperthermia for the treatment of transplanted Walker 256 carcinoma was evaluated. The tumour was infiltrated with the synthesised particles and then treated with an alternating magnetic field. The survival rate was 85% in the studied therapy group of seven animals, while in the control group (without treatment), all animals died. The physicochemical and pharmaceutical properties of the synthesised fluid and the therapeutic results, as seen in the in vivo experiments, provide insights into therapeutic hyperthermia using injected magnetite nanoparticles.     

Patterning of Lyotropic Chromonic Liquid Crystals by Photoalignment with Photonic Metamasks

Controlling supramolecular self‐assembly in water‐based solutions is an important problem of interdisciplinary character that impacts the development of many functional materials and systems. Significant progress in aqueous self‐assembly and templating has been demonstrated by using lyotropic chromonic liquid crystals (LCLCs) as these materials show spontaneous orientational order caused by unidirectional stacking of plank‐like molecules into elongated aggregates. In this work, it is demonstrated that the alignment direction of chromonic assemblies can be patterned into complex spatially‐varying structures with very high micrometer‐scale precision. The approach uses photoalignment with light beams that exhibit a spatially‐varying direction of light polarization. The state of polarization is imprinted into a layer of photosensitive dye that is protected against dissolution into the LCLC by a liquid crystalline polymer layer. The demonstrated level of control over the spatial orientation of LCLC opens opportunities for engineering materials and devices for optical and biological applications.     

Enhancing the coverage of the urinary metabolome by sheathless capillary electrophoresis-mass spectrometry

Sheathless capillary electrophoresis-mass spectrometry (CE-MS), using a porous tip sprayer, is proposed for the first time for highly sensitive metabolic profiling of human urine. A representative metabolite mixture and human urine were used for evaluation of the sheathless CE-MS platform. For test compounds, relative standard deviations (RSDs) for migration times and peak areas were below 2% and 12%, respectively, and an injection volume of only ～8 nL resulted in detection limits between 11 and 120 nM. Approximately 900 molecular features were detected in human urine by sheathless CE-MS whereas about 300 molecular features were found with classical sheath-liquid CE-MS. This difference can probably be attributed to an improved ionization efficiency and increased sensitivity at low flow-rate conditions. The integration of transient-isotachophoresis (t-ITP) as an in-capillary preconcentration procedure in sheathless CE-MS further resulted in subnanomolar limits of detection for compounds of the metabolite mixture, and more than 1300 molecular features were observed in urine. Compared to the classical CE-MS approaches, the integration of t-ITP combined with the use of a sheathless interface provides up to 2 orders of magnitude sensitivity improvement. Hence, sheathless CE-MS can be used for in-depth metabolic profiling of biological samples, and we anticipate that this approach will yield unique information in the field of metabolomics.     

Phase Formation in Sintering of Materials Based on Silicon Nitride with Li2CO3 and AlN Additives

We have studied the phase formation processes occurring in sintering of materials based on silicon nitride with lithium carbonate and aluminum nitride or Al powder additives. We have studied samples of different compositions that were sintered at 1450, 1550, and 1750°C under a nitrogen atmosphere. We have established that the phase composition depends on the sintering temperature, the composition of the starting charge, and also the amount and the nature of the Al-containing additives.     

High-temperature strength behavior of tantalum diboride to 2000°C

This study investigated the high-temperature strength of spark plasma sintered tantalum diboride (TaB₂) for the first time. TaB₂ exhibited a unique elastic fracture behavior below 1900°C, unlike other transition metal diborides. The consolidation process involved spark plasma sintering at 2000–2200°C yielding dense TaB₂ samples. The flexural strength was measured at elevated temperatures up to 2000°C, showing a quite high flexural strength of 400 ± 20 MPa at 1900°C. These findings provide valuable insights into the high-temperature behavior of TaB₂, highlighting its potential for advanced applications.     

Pushing the Boundaries of Structural Heterogeneity with the Lipid A of Marine Bacteria Cellulophaga

Marine bacteria, which are often described as chemical gold, are considered an exceptional source of new therapeutics. Considerable research interest has been given to lipopolysaccharides (LPSs), the main components of the Gram-negative outer membrane. LPS and its lipid A portion from marine bacteria are known to exhibit a tricky chemistry that has been often associated with intriguing properties such as behaving as immune adjuvants or anti-sepsis molecules. In this scenario, we report the structural determination of the lipid A from three marine bacteria within the Cellulophaga genus, which showed to produce an extremely heterogenous blend of tetra- to hexa-acylated lipid A species, mostly carrying one phosphate and one D-mannose on the glucosamine disaccharide backbone. The ability of the three LPSs in activating TLR4 signaling revealed a weaker immunopotential by C. baltica NNO 15840^T and C. tyrosinoxydans EM41^T, while C. algicola ACAM 630^T behaved as a more potent TLR4 activator.     

Promising Antifungal and Antibacterial Agents Based on 5-Aryl-2,2′-bipyridines and Their Heteroligand Salicylate Metal Complexes: Synthesis,Bioevaluation, Molecular Docking

A series of new 5-aryl-2,2′-bipyridines and their (polyfluoro)salicylate complexes of Cu(II), Co(II) and Mn(II) were synthesized. Their antimicrobial activity was evaluated in vitro against six strains of Trichophytons, E. floccosum, M. canis, C. ablicans and Gram-negative bacteria N. gonorrhoeae. Among azo-ligands, Ph-bipy and Tol-bipy showed promising antifungal activity (minimum inhibitory concentration (MIC)<0.8–27 μM). Their antifungal action was found can be realized via binding Fe(III) ions. Tol-bipy suppressed growth of Gram-positive bacteria S. aureus, S. aureus MRSA and their monospecies biofilms (MIC 6–16 μM). Using molecular docking, the anti-staphylococcal action mechanism based on the inhibition of S. aureus DNA gyrase GyrB was proposed for the lead compounds. Among metal complexes, Cu(II) and Mn(II) complexes based on tetrafluorosalicylic acid and Tol-bipy or Ph-bipy had the high antifungal activity (MIC<0.24–32 μM). Mn(SalF₄−2H)₂(Tol-bipy)₂] suppressed the growth of seven Candida strains at MIC 12–24 μM. [Cu(Sal−2H)(Ph-bipy)] and [Cu(SalF₃−2H)(Ph-bipy)₂] showed the promising anti-gonorrhoeae activity (MIC 4.2–5.2 μM). (Cu(SalF_n−2H)(Tol-bipy)₂], [Cu(SalF₄−2H)(Ph-bipy)₂] and [Cu(SalF₃−2H)(Ph-bipy)₂]) were found active against the bacteria of S. aureus, S. aureus MRSA and their biofilms (MIC 2.4–41.4 μM). The most active compounds were tested for toxicity in vitro against human embryonic kidney (HEK-293) cells and in vivo experiments with CD-1 mice.     

Mithplatins: Mithramycin SA-Pt(II) Complex Conjugates for the Treatment of Platinum-Resistant Ovarian Cancers

DNA coordinating platinum (Pt) containing compounds cisplatin and carboplatin have been used for the treatment of ovarian cancer therapy for four decades. However, recurrent Pt-resistant cancers are a major cause of mortality. To combat Pt-resistant ovarian cancers, we designed and synthesized a conjugate of an anticancer drug mithramycin with a reactive Pt(II) bearing moiety, which we termed mithplatin. The conjugates displayed both the Mg²⁺-dependent noncovalent DNA binding characteristic of mithramycin and the covalent crosslinking to DNA of the Pt. The conjugate was three times as potent as cisplatin against ovarian cancer cells. The DNA lesions caused by the conjugate led to the generation of DNA double-strand breaks, as also observed with cisplatin. Nevertheless, the conjugate was highly active against both Pt-sensitive and Pt-resistant ovarian cancer cells. This study paves the way to developing mithplatins to combat Pt-resistant ovarian cancers.