Tragedija Orest se v marsičem kaže kot »najbolj evripidovska izmed vseh Evripidovih iger«. Njena slogovna in tematska kompleksnost zato omogočata zelo raznovrstne interpretacije. Prispevek najprej ...predstavi koncepta pobožnosti in tragične napake v grški ljudski religiji in tragiški misli. Temu pa sledi raziskava, kako ta koncepta vplivata na interpretacijo Evripidove različice mita o Tantalidih, značajev in dejanj dramskih oseb ter končnega preobrata. Ta analiza kaže, da pesnik v svojem zadnjem nagovoru Atencev (drama je bila uprizorjena leta 408 pr. n. št.) prikazuje večno kaotično stanje vojne, ki ga ljudje niso sposobni preseči. Zato je treba kot resno in politično motivirano sporočilo drame razumeti tudi končni preobrat in Apolonov nastop, ki osmisli preteklost in človeško trpljenje, poveže sprte strani ter jim zapove, naj častijo mir.
O prisotnosti Mikencev na področju zahodne Anatolije, njenih obalah in otokih med začetkom 15. in koncem 12. stol. pr. n. št. pričajo arheološki viri. O naravi stikov med Hetiti in Mikenci na ...»periferiji« obeh kultur je (ob predpostavki, da v hetitskih besedilih izpričano ime Ahhiyawa označuje Mikence) mogoče sklepati na osnovi pisnih virov. Prispevek prinaša pregled in interpretacijo hetitskih besedil z omembami Ahhiyawe, arheoloških virov o Mikencih na področju Anatolije in Hetitih na področju Egejskega morja, nato shematično prikaže naravo stikov med Mikenci in Hetiti in opozori na vprašanja, ki jih identifikacija Ahhiyawe z mikenskim svetom prinaša.
2,5-Furandicarboxylic acid (FDCA) is one of the top biomass-derived value-added chemicals. It can be produced from fructose and other C6 sugars via formation of 5-hydroxymethilfurfural (HMF) ...intermediate. Most of the chemical methods for FDCA production require harsh conditions, thus as an environmentally friendly alternative, an enzymatic conversion process can be applied.
Commercially available horseradish peroxidase (HRP) and lignin peroxidase (LPO), alcohol (AO) and galactose oxidase (GO), catalase (CAT) and laccase (LAC) were tested against HMF, 2,5-diformylfuran (DFF), 5-hydroxymethyl-2-furoic acid (HMFA) and 5-formyl-2-furoic acid (FFA). Enzyme concentrations were determined based on the number of available active sites and reactions performed at atmospheric oxygen pressure. AO, GO, HRP and LPO were active against HMF, where LPO and HRP produced 0.6 and 0.7% of HMFA, and GO and AO produced 25.5 and 5.1% DFF, respectively. Most of the enzymes had only mild (3.2% yield or less) or no activity against DFF, HMFA and FFA, with only AO having a slightly higher activity against FFA with an FDCA yield of 11.6%. An effect of substrate concentration was measured only for AO, where 20 mM HMF resulted in 19.5% DFF and 5 mM HMF in 39.9% DFF, with a
value of 14 mM. Some multi-enzyme reactions were also tested and the combination of AO and CAT proved most effective in converting over 97% HMF to DFF in 72 h.
Our study aimed at understanding the mechanism of conversion of bio-based HMF to FDCA by different selected enzymes. By understanding the reaction pathway, as well as substrate specificity and the effect of substrate concentration, we would be able to better optimize this process and obtain the best product yields in the future.
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•Six enzymes were tested for the conversion of HMF and its oxidation products.•A Michaelis-Menten kinetic model was constructed based on experimental results.•The model was in good ...agreement with single-enzyme reactions.•Multi-enzyme reactions with two to four enzymes were used for model validation.
Six enzymes were tested against HMF and its oxidation intermediates to determine substrate specificity, product yield and pathways. A Michaelis–Menten kinetic mathematical model was constructed and some rate parameters calculated. The best 2,5-diformylfuran (DFF) productivity was obtained with alcohol oxidase (AO) and 10.0 mM HMF, where 3.0 mM DFF was formed, followed by galactose oxidase (GO) and 10.0 mM HMF with a 0.5 mM DFF yield. Oxygen concentration in solution remained unchanged during processes. Substrate concentration affected only AO, where around 10 mol.% more DFF was formed with 5.0 mM HMF. The model was mostly in good agreement with single-enzyme reactions. Multi-enzyme reactions were used for model validation. The combination of AO and catalase was optimal, converting 10.0 mM HMF to 9.7 mM DFF. Small discrepancy between measured and modeled multi-enzyme reactions was observed due to the exclusion of the specific interactions in mechanisms.
Dilactone ellagic acid (EA) is a polyphenolic compound in various fruits, vegetables, and other biomass structures that has many health-promoting properties. We directly synthesized EA from a gallic ...acid derivative, ethyl gallate. Previously reported methods were utilized, including synthesis with N,N-dimethylammonium N′,N′-dimethylcarbamate (DIMCARB) ionic liquid and 3 different hydroxides with aeration, and in addition, we tested a novel method with 5 different choline chloride (ChCl)-based deep eutectic solvents (DESs) in combination with hydroxide and aeration. Despite our optimization attempts, DIMCARB performed very poorly (<2% yield of EA). On the other hand, the reactions with a 1% NH4OH catalyst resulted in a 50.3% yield of EA with an 85% purity. When 10% DES was added to 1% NH4OH, conversions increased from 50.3% up to 77.5% with an 82.9% purity. It was confirmed that neutral DES reduces the solubility of EA, which importantly decreases the rate of the reverse reaction, partly explaining the drastic increase in the yield. A scale-up of the most efficient DES/NH4OH system was also assessed, reaching a 61.8% yield and a purity of over 80%, respectively, indicating importance of O2 aeration. Finally, a quantitative model of the engineered synthesis process was developed, showing that pH is the most important design factor influencing equilibrium, mechanistic rate kinetics, and the solubility of the product and why the combination of NH4OH and neutral DES works.
Pore formation of cellular membranes is an ancient mechanism of bacterial pathogenesis that allows efficient damaging of target cells. Several mechanisms have been described, however, relatively ...little is known about the assembly and properties of pores. Listeriolysin O (LLO) is a pH-regulated cholesterol-dependent cytolysin from the intracellular pathogen Listeria monocytogenes, which forms transmembrane β-barrel pores. Here we report that the assembly of LLO pores is rapid and efficient irrespective of pH. While pore diameters at the membrane surface are comparable at either pH 5.5 or 7.4, the distribution of pore conductances is significantly pH-dependent. This is directed by the unique residue H311, which is also important for the conformational stability of the LLO monomer and the rate of pore formation. The functional pores exhibit variations in height profiles and can reconfigure significantly by merging to other full pores or arcs. Our results indicate significant plasticity of large β-barrel pores, controlled by environmental cues like pH.
The introductory part of the paper is devoted to the notions case, semantic roles, Sumerograms, Akkadograms and hybrid writings. The main part of the paper presents possible competing uses of ...Akkadographic analytic case markers and Hittite case endings and local adverbs. It further describes the written norm of Akkadographic analytic case markers with Sumerographic and Akkadographic common nouns, numerals, proper nouns and hybrid writings. The paper thus tries to point out that the use and semantics of Akkadographic analytic case markers is more limited than that of Hittite case endings and local adverbs.
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