Amyloids are proteins of a cross-β structure found as deposits in several diseases and also in normal tissues (nails, spider net, silk). Aromatic amino acids are frequently found in amyloid deposits. ...Although they are not indispensable, aromatic amino acids, phenylalanine, tyrosine and tryptophan, enhance significantly the kinetics of formation and thermodynamic stability, while tape or ribbon-like morphology is represented in systems with experimentally detected π-π interactions between aromatic rings. Analysis of geometries and energies of the amyloid PDB structures indicate the prevalence of aromatic-nonaromatic interactions and confirm that aromatic-aromatic interactions are not crucial for the amyloid formation.
Arsenic can be toxic to living organisms, depending not only on the concentration, but also its chemical form. The aim of this study was to determine arsenic concentrations and perform arsenic ...speciation analysis for the first time in honeybees, to evaluate their potential as biomonitors. Highest arsenic concentrations were determined in the vicinity of coal fired thermal power plants (367 µg kg−1), followed by an urban region (213 µg kg−1), with much lower concentrations in an industrial city (28.8 µg kg−1) and rural areas (41 µg kg−1). Until now, honey bees have never been used to study different arsenic species in the environment. For this reason, four extraction procedures were tested: water, hot water at 90 °C, 20% methanol, and 1% formic acid. Water at 90 °C was able to extract more than 90% of the total arsenic from honey bee samples. Inorganic arsenic (the sum of arsenite and arsenate) accounted for 95% of arsenic species in bees from three locations, except the industrial city, where it represented only 80% of arsenic species, while 15% was present as DMA.
Display omitted
•First arsenic speciation analysis in honey bees.•Hot water at 90 °C provided the best extraction efficiency (> 90%).•Inorganic As accounted for 95% of arsenic species in three of four extracts.•In one location significant concentration (15% of speciated As) of DMA was observed.
Homogenized or pooled samples of honey bees are already used for monitoring of metal pollution in the environment for a couple of decades. This is the first study that analyzed the elemental ...composition of individual honey bees. One apiary with 21 hives was used to test in-hive and between-hive differences at the same location. Highest in-hive variability was observed for Al (14.1x), Li (10.3x), V (10.3x), As (8.9x) and Cd (7.9x). For the elements Cu, K, Mg, Na, P, S and Zn the smallest both in-hive (2.3x, 1.8x, 2.0x, 2.2x, 1.9x, 1.7x, 2.4x respectively) as well as between-hive variability (1.5x, 1.4x, 1.4x, 1.6x, 1.4x, 1.4x and 1.5x respectively) was observed. Nonetheless, between-hive variability was statistically significant for all the analyzed elements. We proved that these differences significantly influence comparison of element concentrations in bees from different locations. One hive from Mesić apiary had significantly lower concentrations of Al (hive 18: 18.6 mg kg−1) and U (hive 1: 0.0013 mg kg−1), while at the same time a different hive from the same apiary showed higher concentration of these elements (Al, hive 14: 125 mg kg−1; U, hive 13: 0.012 mg kg−1) compared to another location (thermal power plant, Al: 97 mg kg−1, U: 0.0044 mg kg−1). Therefore, when using honey bees as biomonitors, we recommend a larger number of hives to be sampled at each location to provide an adequate dataset for reliable interpretation of results. Comparing individual bee elemental concentrations, for Na, Mg, P, S, K, Fe, Cu, and Zn negative correlations were found between dry mass of a bee and concentrations of these elements. These negative correlations could be a consequence of higher honey or nectar content in some of the sampled bees. However, this should also be considered when using honey bees as bioindicators.
Display omitted
•First results on elemental composition of individual honey bees.•Certain elements show a high in-hive and/or between-hive variation.•In-hive and between-hive differences influence honey bees use as bioindicators.•Correlations between individual bee mass and element concentrations are shown.
Water molecules from crystal structures archived in the CSD show a relatively large range both in the bond angle and bond lengths. High level
ab initio
calculations at the CCSD(T)/CBS level predicted ...a possibility for energetically low-cost (±1 kcal mol
−1
) changes of the bond angle and bond lengths in a wide range, from 96.4° to 112.8° and from 0.930 Å to 0.989 Å, respectively.
High level
ab initio
calculations predicted a possibility for energetically low-cost (±1 kcal mol
−1
) change of the bond angle and bond lengths in wide range,from 96.4° to 112.8° and from 0.930 Å to 0.989 Å, respectively.
Binuclear {Pd (dien)}2(μ‐pz)(ClO4)4 (Pd1) and {Pd (dien)}2(μ‐pydz)(ClO4)4 (Pd2) complexes, where pz is 1,4‐diazine and pydz is 1,2‐diazine bridging ligands and dien (diethylenetriamine) is a ...tridentately coordinated triamine ligand, were synthesized and characterized using elemental analysis, NMR (1H and 13C) spectroscopy, and UV–Vis spectrophotometry. Electronic absorption spectrophotometry and fluorescence spectroscopy were used to study the interactions of the prepared Pd1 and Pd2 complexes with deoxyribonucleic acid (CT‐DNA) and bovine serum albumin (BSA). According to the UV–Vis spectrophotometric data, the complexes interact with CT‐DNA and bind to the BSA as a possible carrier to the target site. The antitumor properties of the tested palladium compounds were evaluated on three types of human cancer cells, namely, squamous cell carcinoma cells SCC‐4, cervical carcinoma cells HeLa and colorectal carcinoma cells HCT116, and one type of malignantly unchanged cells, MRC‐5 fibroblasts. The highest cytotoxicity was shown by the Pd1 compound against SCC‐4 cell, with an IC50 value of 5.4 ± 1.2 μM. The results showed that the cytotoxic potential against SCC‐4 cells of our new palladium complexes Pd1 and Pd2 was comparable with the cytotoxic potential of cisplatin and oxaliplatin. However, Pd1 and Pd2 displayed significantly lower cytotoxicity in comparison with cisplatin and oxaliplatin against non‐malignant cells, fibroblasts MRC5, so these results may suggest that local and systemic complications of antitumor therapy could be reduced and/or avoided. Both compounds selectively decreased the viability of SCC‐4 cells by induction of apoptosis. Also, Pd1 and Pd2 induced S‐phase cell cycle arrest in human SCC‐4 cells, so that could be another mechanism to halt the uncontrolled growth and division of cancer cells. Moreover, the precise molecular mechanism of Pd1 and Pd2 complexes‐induced apoptosis was the activation of the intrinsic signaling pathway of apoptosis, which also included activation of caspase‐3. Therefore, our new palladium (II) complexes might have a promising role as the potential future cytostatic agents.
Pd1 and Pd2 selectively decrease the viability of cancer cells via cell cycle arrest and activation of caspase‐dependent mitochondrial apoptotic pathway.
The study of crystal structures from the Cambridge Structural Database (CSD) shows that most of p-phenol/p-phenol and toluene/toluene stacking interactions are at large horizontal displacements ...(offsets) as well as benzene/benzene interactions. The interactions at large horizontal displacements are stabilized by the addition of simultaneous interactions in supramolecular structures in crystals. The stacking p-phenol/p-phenol tends to be orientated in a parallel and antiparallel fashion, while stacking toluene/toluene is almost all in an antiparallel orientation. It is in accordance with calculated interaction energies. Namely, the strongest interaction energies for parallel and antiparallel phenol/phenol dimers are −5.12 and −4.40 kcal/mol, at offsets of 1.5 and 3.0 Å, respectively, while for parallel and antiparallel toluene/toluene dimers, energies are −3.98 and −5.39 kcal/mol, at offsets of 3.0 Å. These interactions are stronger than benzene/benzene stacking (−2.85 kcal/mol), as a consequence of the presence of the substituents. Similar to benzene/benzene stacking, interactions for phenol/phenol and toluene/toluene stacking at large offsets (4.0 Å) can be strong, stronger than −2.0 kcal/mol.
Honey bees are social insects that show division of labor and sexual dimorphism. Female honey bees differentiate in two different castes, queens or worker bees, while males are called drones. Worker ...bees have different tasks in the hive including collection of food, its processing, caring for brood, protecting the hive, or producing wax. The drones' only role is to mate with a virgin queen. Many studies have dealt with differences in physiology, behavior, and morphology of workers and drones. This is the first study that demonstrates differences in element accumulation and composition between workers and drones honey bees. Using inductively coupled plasma mass spectrometry, we found that worker honey bees have higher concentrations of most elements analyzed. Drones had higher concentrations of elements essential to bees, Na, P, S, Zn, Cu, and especially Se (2.2 × higher), which is known to be important for sperm quality and fertility in many animals. Until now higher Se content was not observed in male insects. These differences can be attributed to different environmental exposure, reproductive role of drones, but mostly to the food workers and drones consume. Worker bees feed on bee bread, which is rich in minerals. Drones are fed food pre-processed by worker bees.
The hydrogen bonds of free and coordinated amino acids with water molecule were studied by analyzing data in the crystal structures from the Cambridge Structural Database (CSD) and by quantum ...chemical calculations. The CSD data indicate bifurcated NH/O hydrogen bonds and O1/HO hydrogen bonds of coordinated oxygen. The O/HO hydrogen bonds of free zwitterions and non-coordinated carbonyl oxygen (O2/HO) in metal complexes form primarily linear, non-bifurcated hydrogen bonds. Calculated M06L-GD3/def2-TZVPP interaction energies for free zwitterions (glycine, cysteine, phenylalanine and, serine) and water molecule are in the range from −5.1 to −9.6 kcal/mol for NH/O and from −6.9 to −7.6 kcal/mol for O/HO interactions. Coordinated amino acids in neutral octahedral cobalt(III) complexes have NH/O interaction energies ca. -7.4 kcal/mol, independent of the amino acid. The singly and doubly charged complexes have stronger NH/O interactions; the strongest has energy of −16.9 kcal/mol. In the case of O1/HO hydrogen bond, the interaction energy decreases upon coordination; interactions are quite weak for neutral complexes (−2.2 to −2.6 kcal/mol). For O2/HO hydrogen bonds, all amino acids except serine show slightly stronger interaction in singly negative complexes (−6.3 to −8.0 kcal/mol), while interactions are weaker for neutral complexes (−2.8 to −4.4 kcal/mol), comparing to zwitterions.
Data give inside on the geometry and energy of hydrogen bonds in the second coordination sphere of amino acid complexes, as well as influence of amino acids coordination on the geometry and energy of the amino acid's hydrogen bonds. Display omitted
•The hydrogen bonds of non-coordinated and coordinated amino acids were investigated.•The data in the Cambridge Structural Database (CSD) were analyzed.•Interaction energies of linear and optimized hydrogen bonds were calculated.•NH/O hydrogen bonds are stronger than both O1/HO and O2/HO types.•Type of the amino acid does not influence the interaction energy significantly.
Hydrogen bonds of glycine complexes were calculated using quantum chemistry calculations at M06L-GD3/def2-TZVPP level and by analyzing the crystal structures from the Cambridge Structural Database ...(CSD). One hydrogen bond where amino acid plays the role of the H-donor (NH/O), and two where it plays the role of the H-acceptor (O1/HO, O1 is a coordinated oxygen atom, and, O2/HO, O2 is a non-coordinated oxygen atom) were investigated. The calculations were done on octahedral nickel(II), square pyramidal copper(II), square planar copper(II), palladium(II), and platinum(II) glycine complexes with different charges adjusted using water(s) and/or chlorine ion(s) as the remaining ligands. For NH/O hydrogen bond, interaction energies of neutral complexes are the weakest, from -5.2 to -7.2 kcal/mol for neutral, stronger for singly positive, from -8.3 to -12.1 kcal/mol, and the strongest for doubly positive complex, -16.9 kcal/mol. For O1/HO and O2/HO interactions, neutral complexes have weaker interaction energies (from -2.2 to -5.1 kcal/mol for O1/HO, and from -3.7 to -5.0 kcal/mol for O2/HO), than for singly negative complexes (from -6.9 to -8.2 kcal/mol for O1/HO, and from -8.0 to -9.0 kcal/mol for O2/HO). Additionally to the complex charge, metal oxidation number, coordination number, and metal atomic number also influence the hydrogen bond strength, however, the influence is smaller.
PDF
