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Protein modifications and ionic strength show the difference between protein-mediated and solvent-mediated regulation of biomolecular condensation
No full textBiomolecular condensation is an important mechanism of cellular compartmentalization without membranes. Formation of liquid-like condensates of biomolecules involves protein-protein interactions working in tandem with protein-water interactions. The balance of these interactions in condensate-forming proteins is impacted by multiple factors inside of a living organism. This work investigates the effects of post-translational modifications (PTMs) and salt concentration as two such perturbing factors on the protein Fused in Sarcoma (FUS), an RNA binding protein. The protein was obtained from two expression systems differing by their capability to add PTMs to the protein, bacterial and insect cell. Attenuated total reflection Terahertz spectroscopy is used to probe the solvation behavior in condensates formed from FUS protein with and without PTMs at 100 mM and 2.5 M KCl. The results show that while PTMs impact the phase-separating propensity, they do not alter protein solvation in the condensate. On the other hand, salt concentration was found to alter the stiffness of the water hydrogen bond network. These findings have implications for biomolecular condensates chemistry, showing that condensate molecular organization is perturbed by fluctuations in solvent properties
Fast and selective protein modification with iron-substituted polyoxometalates via a radical pathway
No full textOxidative modifications of proteins are crucial post-translational modifications that profoundly impact their structure, function, and turnover. Developing chemical methods that selectively induce oxidative protein modifications and cleavage would significantly facilitate elucidation of these oxidative processes, benefiting our understanding of disease mechanisms, identifying novel therapeutic targets, and advancing biotechnological applications. In this work, we demonstrate that all-inorganic discrete polyoxometalate (POM) clusters stabilize redox active metal centers such as Fe(III) and Mn(III) under physiological pH and temperature (pH = 7.5, 37 °C), enabling the generation of reactive oxygen species (ROS) under mild aqueous conditions. Specifically, we show that catalytic amounts of the iron-substituted POM K7[FeIII(α2-P2W17O61)(H2O)] (FeIIIWD), in the presence of ascorbate (Asc), rapidly induce selective oxidation and cleavage of hen egg-white lysozyme (HEWL) in four narrow regions of the protein sequence. The protein cleavage sites are all located near the interaction sites of MIIIWD (M = Mn or Fe) catalysts with the protein surface. In contrast, the manganese-substituted POM K7[MnIII(α2-P2W17O61)(H2O)] (MnIIIWD) shows no similar catalytic activity, pointing towards a different radical mechanism. These findings highlight the potential of well-tailored inorganic clusters to facilitate selective catalytic processes, enabling iron to target specific regions of a protein sequence without relying on coordination sites on the protein surface, while offering flexibility in reaction conditions
Molecular and crystal structures of Cd(II) complexes with pyridine-based 1,3-selenazolyl/thiazolyl-hydrazones
No full textNovel Cd(II) complexes, [Cd(HLSe1)2](ClO4)2 (1–Se) and [Cd(HLS1)2](ClO4)2 (1–S) (Figure 1), with (1,3-selenazol/thiazol-2-yl)hydrazones were prepared and characterized by a single crystal X-ray diffraction analysis. The complexes crystallize in the monoclinic C2/c space group. The coordination number of Cd(II) is six in both cases, and the ligands are tridentately coordinated in the neutral form via NNN donor atoms set: pyridine, imine and nitrogen atoms from the selenazole or thiazole rings. The angular distortion from the regular octahedral geometry of the complexes can be attributed to the constraints imposed by the described ligand coordination. In the outer sphere of the complexes, there are two perchlorate anions. In both cases, Cd(II) ion resides in a special position with site symmetry 2 (Wyckoff letter e). Hirshfeld surfaces and 2D pseudosymmetric fingerprint plots were constructed to analyse the crystal packings, which are dominated by classical and non-classical hydrogen interactions between the complex cations and perchlorate anions. Based on the data analysis obtained from spectrophotometric titration, the stability of the formed Cd(II) complexes was determined. The obtained values of the cumulative stability constant indicate significant stability of the investigated compounds
Application of BSA-modified silica for solid phase extraction of progesterone from river water samples
No full textThis study reports the development and application of bovine serum albumin (BSA)-modified silica gels as selective and durable sorbents for the solid-phase extraction (SPE) of progesterone from river water samples. One of the sorbents was used for SPE preconcentration followed by progesterone quantification in a sample collected from the Danube River. The standard addition method followed by high-performance liquid chromatography (HPLC-DAD) detection enabled the quantification of progesterone at a concentration of 143.0 ± 4.0 ng/L. At elevated progesterone concentrations (1.0 to 2.0 × 10-7 M), recoveries approached 100 %, demonstrating the high efficiency of the developed extraction sorbents. The overall method recovery ranged from 91.4 to 101.0 %, confirming the method’s accuracy and robustness. Furthermore, under optimized SPE conditions, developed sorbents were highly selective towards progesterone compared to other reproductive hormones. The sorbents exhibited excellent long-term stability, with no significant change in binding efficiency observed over a four-year period (variation lower than 3 %), maintaining consistent recoveries of 94–96 %. Newly developed BSA-modified silica sorbents represent a promising tool for trace analysis of steroid hormones, as well as for their routine environmental monitoring
Genetic diversity and essential oils variability of Satureja subspicata Bartl. ex Vis. natural populations
No full textSatureja subspicata Bartl. ex Vis. (Lamiaceae) is an endemic species distributed along the Dinaric mountain range, used in traditional medicine. Due to its medicinal and aromatic properties, this plant is exploited in its natural habitat. This work aimed to evaluate the genetic diversity of natural populations of both S. subspicata subspecies using essential oils (EO) variability and inter-simple sequence repeat (ISSR) molecular markers. Also, to develop tools and biomarkers for the authentication of subspecies. The EO profile showed an abundance of sesquiterpenes and the absence of a single dominant compound. Based on α-pinene, γ-muurolene, caryophyllene oxide, and viridiflorol populations belonging to different subspecies could be differentiated. Additionally, higher amounts of caryophyllene oxide were characteristic of subsp. liburnica. Analysis of ISSR markers showed differentiation of populations and two subspecies due to the isolation by distance model, and revealed two populations with mixed ancestry in parts where the distribution areas of the two subspecies overlap. The observed genetic variability and consistency of traits give a basis for breeding strategies, domestication of specific EO profiles. Both markers can be used in assessing genetic diversity, hybrid detection between two subspecies, as well as between other sympatric Satureja species in natural populations
CH/O hydrogen bonds in the second coordination sphere of bipyridine complexes with water: stronger than classical water–water hydrogen bonds
No full textAlthough CH/O interactions are generally recognized as weak noncovalent interactions, CH/O interactions in the second coordination sphere of 2,2′-bipyridine (bipy) complexes are surprisingly strong. Coordinated bipy ligands can form strong interactions; the calculated interaction energies for CH/O interactions of neutral cobalt(II), copper(II), and palladium(II) complexes with a water molecule range from −3.00 to −5.57 kcal/mol. The interaction energies are influenced by the coordination number of the complex and by the position of the interacting hydrogen atom. As the coordination number decreases, the CH/O interaction becomes stronger, while bifurcated interactions are stronger than linear ones. The strongest calculated interaction is a bifurcated interaction in a square-planar palladium(II) complex. The calculated energies and distances of CH/O interactions in bipy complexes are consistent with the data observed by analyzing crystal structures from the Cambridge Structural Database. These findings suggest that such interactions could be relevant for the design of new materials and functional molecular systems where noncovalent bonding plays a key role
Employing microalga Chlorella sorokiniana in the biosynthesis of paramagnetic and catalytically functional manganese cluster
No full textFinding vehicles for biosynthesis of metal clusters with advantageous magnetic and catalytic properties is an important industrial and environmental task. We have found previously that green microalga Chlorella sorokiniana produces a multivalent Mn-O cluster with structure that is similar to photosynthetic oxygen-evolving complex (OEC). Here we reported magnetic and redox properties and the site of accumulation of this cluster, and we proposed the mechanisms of biosynthesis and the protocol for extraction. The cluster was paramagnetic even at room temperature, with an antiferromagnetic transition at ∼13 K. The separation between ground and excited state of ΔE ≈ 15.0 cm−1 matched the separation energy of OEC in S2 state. Nano X-ray fluorescence microscopy and 31P NMR showed that the cluster is accumulated in acidocalcisomes, a lysosome-type organelles rich in polyphosphates. The conditions in these organelles resemble the settings of chemical synthesis of OEC mimics, including mildly acidic pH and the availability of Ca2+ ions. Polyphosphates are likely to play a role of stabilizing ligands and modulators of redox properties of Mn2+ in the cluster synthesis. The cluster shares redox potentials with OEC and showed catalase-like activity. However, we could not confirm OEC-like performance because the cluster was prone to degradation by oxidizing agents in the presence of organic residue in the extract. The biosynthesis showed an overall yield of ∼25 % and appears to be cost-competitive with chemical synthesis. This study shows that metabolic trades of selected microalgae can be employed in the green synthesis of catalytically functional clusters
Integrative high-performance thin-layer chromatography‒bioautography and Fourier transform infrared spectroscopy analysis for exploring the cosmeceutical potential of Serbian medicinal plants
No full textThe increasing demand for natural and sustainable cosmetic products has fueled interest in plant-based ingredients. Skin aging, driven by oxidative damage and enzymatic overactivation, results in wrinkles, sagging, and pigmentation disorders. The proposed study targeted radical scavenging activity and key hyperpigmentation enzymes such as tyrosinase to develop effective anti-aging and skin-whitening agents. We employed an integrated analytical approach combining high-performance thin-layer chromatography (HPTLC) with bioassays (HPTLC‒2,2-diphenyl-1-picrylhydrazyl [DPPH] and HPTLC‒tyrosinase) as an ecofriendly, rapid, and cost-effective tool for (bio)screening of natural plant extracts. The structural characterization of active compounds was further achieved using attenuated total reflectance‒Fourier transform infrared spectroscopy (ATR‒FTIR). Additionally, total phenolic and total flavonoid content were determined to assess bioactive content. Principal component analysis (PCA) enabled the classification of extracts based on their chemical signatures. Our results demonstrated that Rosaceae plants, including hawthorn and dog rose, exhibit promising antipigmentation properties, whereas agrimony (Rosaceae) and wall germander (Lamiaceae) showed potent antioxidative activity. The HPTLC‒DPPH-tyrosinase‒ATR‒FTIR approach proposed bioactive compounds. This integrative HPTLC approach highlights the potential of Serbian medicinal plants as sustainable sources for innovative cosmeceuticals
Unveiling the paleosalinity constraints on southern peri-Pannonian Lower Miocene lacustrine systems in Serbia and Bosnia and Herzegovina: Lopare (Dinaride Lake System) versus Toplica basin (Serbian Lake System)
No full textEarly Neogene saline lakes were widely developed across Central Paratethys, particularly across its „Dinaride-Anatolide“ landbridge (area of Dinarides, Balkans). The constraints on Lopare (western part of Jadar block; eastern Bosnia and Herzegovina) and Toplica (Jastrebac Mt., central Serbia) Neogene paleolakes provide a better understanding of deep-time climate evolution. The study focused on early Neogene paleolacustrine configuration, paleogeography, and the factors affecting a considerable paleosalinity increase. The study integrated available records on the predominantly Lower Miocene sedimentary sequence by analyzing and interpreting several paleosalinity markers (inorganic geochemical proxies, mineralogical data). The constraints on paleosalinity markers are afterward coupled with rather complex tectonic inferences. The two wellbores drilled in the Lopare and Toplica basins expose Neogene sections from which the critical paleosalinity markers are extracted (drillhole depths up to 350 and 1000 m, respectively). The mineral searlesite (NaBSi2O5(OH)2), and high B/Ga, markers of alkaline and arid paleoenvironmental lacustrine conditions, suggested intense evaporation (frequent drought periods). The evaporation was associated with paleoclimatic conditions during the Miocene Climatic Optimum. The Early Neogene arid climate and frequent evaporation episodes resulted in significant salinization of the Lower Miocene Lopare lacustrine sequence. The salinity in the Lopare sequence changed its character between brackish and saline, as evidenced by S/TOC and Ca/(Ca + Fe) ratios (TOC—Total Organic Carbon). At the same time, the salinity in the early Toplica basin was significantly lower and characterized by freshwater and brackish environments. The salinity variations between Toplica and Lopare were further exposed by Fe/(Ca + Mg), (Al + Fe)/(Ca + Mg), and C-value, yielding the change in the (paleo)water column. These markers further indicated the influence of warm climate conditions, consistent with the Miocene paleoclimatic record. Regarding paleogeography and Early Neogene tectonics, the results showed that before the Middle Miocene Badenian transgression, the Paratethyan Sea had no interference with the investigated intramontane lacustrine basins
Innovative analytical methodology for skin anti-aging compounds discovery from plant extracts: Integration of High-Performance Thin-Layer Chromatography-in vitro spectrophotometry bioassays with multivariate modeling and molecular docking
No full textSkin aging, characterized by reduced elasticity, wrinkles, and changes in pigmentation, presents significant
challenges in the cosmetics industry. Identifying compounds that can help mitigate these effects is crucial to
developing effective anti-aging treatments and improving skin health. An advanced analytical approach for
identifying skin anti-aging compounds within complex natural mixtures must be developed to achieve this.
This study introduces a state-of-the-art methodology that combines High-Performance Thin-Layer Chroma
tography (HPTLC) and in vitro skin anti-aging spectrophotometry bioassays with regression multivariate analysis
and molecular docking. The proposed methodology integrates spectrophotometric assays for tyrosinase inhibi
tion (anti-pigmentation), elastase inhibition (anti-wrinkle), and radical scavenging capacity (DPPH•/ ABTS• as
says) with analytical signals obtained from HPTLC chromatograms using Partial Least Squares models (PLS). The
PLS models for predicting elastase inhibition and antioxidative capacity showed high accuracy with minimal
errors. This study introduces an innovative approach combining HPTLC profiling and PLS regression to identify
single phenolic compounds/bands responsible for anti-aging effects. In addition, identified bioactives were
submitted to molecular docking studies to elucidate the enzyme inhibition mechanisms of elastase and confirm
our approach. This integrated, simple, cost-effective, and high-throughput approach represents a significant
advancement in the discovery of anti-aging compounds, with promising implications for future skincare and
therapeutic applications