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The protection of continuous drinking water supply is really important all over the world, also in Hungary. Many kinds of hazardous chemicals could pollute the natural water resources, arsenic is one of the most occurring pollutant in Hungary. Recently, an ethylene-vinyl alcohol copolymer based arsenic removal adsorbent has been developed. During the manufacturing process hazardous waste water is produced, which is burned in the incineration plant, so this open production process needs fresh solvent every time. However, if the different fraction of the waste water is separated by distillation both the volume of the hazardous waste water can be reduced extremely and the recovered solvent and water can be reused in the manufacturing process. Beside analytical measurements Life Cycle Sustainability Assessment (LCSA) was prepared to identify and compare the environmental, economic and social effects of the current technology and the new one. The results proved that the technology closed by distillation is better than the current open one in each aspect of LCSA. [ABSTRACT FROM AUTHOR]

A general and versatile strategy has been developed for the functionalization of the carbocyclic core of the isoquinoline. This regioexhaustive approach employs electrophilic halogenation as a toolbox methodology and delivers highly decorated intermediates that can be further elaborated toward medicinally relevant building blocks or natural products. [ABSTRACT FROM AUTHOR]

The cis-trans isomerization of amide bonds leads to wide range of structural and functional changes in proteins and can easily be the rate-limiting step in folding. The trans isomer is thermodynamically more stable than the cis, nevertheless the cis form can play a role in biopolymers' function. The molecular system of N-methylacetamide · 2H2O is complex enough to reveal energetics of the cis-trans isomerization at coupled cluster single-double and coupled cluster single-double and perturbative triple [CCSD(T)] levels of theory. The cis-trans isomerization cannot be oversimplified by a rotation along ω, since this rotation is coupled with the N-atom pyramidal inversion, requesting the introduction of a second dihedral angle "α." Full f(ω,α) potential energy surfaces of the different amide protonation states, critical points and isomerization reaction paths were determined, and the barriers of the neutral, O-protonated and N-deprotonated amides were found too high to allow cis-trans interconversion at room temperature: ∼85, ∼140, and ∼110 kJ mol-1, respectively. For the N-protonated amide bond, the cis form (ω = 0°) is a maximum rather than a minimum, and each ω state is accessible for less than ∼10 kJ mol-1. Here we outline a cis-trans isomerization pathway with a previously undescribed low energy transition state, which suggests that the proton is transferred from the more favorable O- to the N-protonation site with the aid of nearby water molecules, allowing the trans → cis transition to occur at an energy cost of ≤11.6 kJ mol-1. Our results help to explain why isomerase enzymes operate via protonated amide bonds and how N-protonation of the peptide bond occurs via O-protonation., (© 2023 Author(s). Published under an exclusive license by AIP Publishing.)

A large group of hormones are stored as amyloid fibrils in acidic secretion vesicles before they are released into the bloodstream and readopt their functional state. Here, we identify an evolutionarily conserved hexapeptide sequence as the major aggregation-prone region (APR) of gastrointestinal peptides of the glucagon family: xFxxWL. We determine nine polymorphic crystal structures of the APR segments of glucagon-like peptides 1 and 2, and exendin and its derivatives. We follow amyloid formation by CD, FTIR, ThT assays, and AFM. We propose that the pH-dependent changes of the protonation states of glutamate/aspartate residues of APRs initiate switching between the amyloid and the folded, monomeric forms of the hormones. We find that pH sensitivity diminishes in the absence of acidic gatekeepers and amyloid formation progresses over a broad pH range. Our results highlight the dual role of short aggregation core motifs in reversible amyloid formation and receptor binding., (© 2023. The Author(s).)

The amyloid formation of the folded segment of a variant of Exenatide (a marketed drug for type-2 diabetes mellitus) was studied by electronic circular dichroism (ECD) and NMR spectroscopy. We found that the optimum temperature for E5 protein amyloidosis coincides with body temperature and requires well below physiological salt concentration. Decomposition of the ECD spectra and its barycentric representation on the folded-unfolded-amyloid potential energy surface allowed us to monitor the full range of molecular transformation of amyloidogenesis. We identified points of no return (e.g.; T=37 °C, pH 4.1, c E5 =250 μm, c NaCl =50 mm, t>4-6 h) that will inevitably gravitate into the amyloid state. The strong B-type far ultraviolet (FUV)-ECD spectra and an unexpectedly strong near ultraviolet (NUV)-ECD signal (Θ ≈275-285   nm ) indicate that the amyloid phase of E5 is built from monomers of quasi-elongated backbone structure (φ≈-145°, ψ≈+145°) with strong interstrand Tyr↔Trp interaction. Misfolded intermediates and the buildup of "toxic" early-stage oligomers leading to self-association were identified and monitored as a function of time. Results indicate that the amyloid transition is triggered by subtle misfolding of the α-helix, exposing aromatic and hydrophobic side chains that may provide the first centers for an intermolecular reorganization. These initial clusters provide the spatial closeness and sufficient time for a transition to the β-structured amyloid nucleus, thus the process follows a nucleated growth mechanism., (© 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)