Coalgebra learning via duality

Automata learning is a popular technique for inferring minimal automata through membership and equivalence queries. In this paper, we generalise learning to the theory of coalgebras. The approach relies on the use of logical formulas as tests, based on a dual adjunction between states and logical theories. This allows us to learn, e.g., labelled transition systems, using Hennessy-Milner logic. Our main contribution is an abstract learning algorithm, together with a proof of correctness and termination

Oxidation Processes of N-methylguanines

The oxidation processes of N-methylguanines were investigated in both experimental and\ntheoretical way. Voltammetric oxidation potentials of guanine and its methyl analogues,\nacquired on polymer pencil graphite electrode (pPeGE), were compared with the HOMO\n(SOMO) energies calculated by density functional (DFT) methods. Our study contributes to\nunderstanding not only the oxidation processes of methylated guanines but also their role in\nepigenetics

Antyutleniacze i ich aktywność środowiskowa. Wpływ zwiążków drobnomolekularnych na proteinę

The aim of this study was to evaluate the relationships between the chemical structure of tea catechins and their binding affinities to HSA (Human Serum Albumin) by fluorescence quenching method at pH 7.4 and 37°C. The quenching constants (Kq), binding constants (Kb), and free energy changes (∆G0) were determined for the tested systems. The presented study contributes to the current knowledge in the area of protein-ligand binding, particularly tea catechin-HSA interactions.Celem pracy była ocena zależności między strukturą chemiczną katechin herbaty i ich powinowactwem do HSA (albumina ludzkiej surowicy) za pomocą metody wygaszania fluorescencji przy pH 7,4 i w temperaturze 37°C. Dla badanych układów wyznaczono stałą szybkości wygaszania (Kq), stałą wiązania (Kb) i zmiany entalpii swobodnej (∆G0). Prezentowana praca poszerza aktualny stan wiedzy na temat wiązania białko - ligand, zwłaszcza interakcji katechiny - HSA

Wrażliwość rodziny Lemnaceae na chrom i cynk

The aim of study was to optimize alternative acute toxicity tests involving toxic compounds of Cr(VI) and Zn(II) and two representatives of the Lemnaceae species (Lemna gibba and Spirodela polyrhiza) as testing organisms and to compare their relative sensitivity with Lemna minor and Daphnia magna. The most sensitive organism to both metals was D. magna. The highest duckweed sensitivity to Cr(VI) and Zn(II) was determined for S. polyrhiza and L. gibba, respectively. The compound of Cr(VI) provided significantly higher toxicity effect towards the testing organisms than Zn(II). L. gibba proved the most suitability for assessment of environmental quality due to the highest duckweed sensitivity. In contrast, L. minor and S. polyrhiza showed the lowest sensitivity to Cr(VI) and Zn(II), respectively. It was probably caused by their antioxidant ability, and thus they may be the most effective for removal of metals from water environment.Celem pracy była optymalizacja alternatywnych testów ostrej toksyczności z udziałem toksycznych związków Cr(VI) i Zn(II) i dwóch przedstawicieli gatunku Lemnaceae (Lemna gibba i Spirodela polyrhiza) jako organizmów testowych i porównanie ich względnej czułości w stosunku do Lemna minor i Daphnia magna. Organizmem najbardziej wrażliwym na oba metale była D. magna. Największą wrażliwość na Cr(VI) i Zn(II) stwierdzono odpowiednio dla L. gibba i S. polyrhiza. Związek chromu(VI) powodował silniejszy efekt toksyczny w organizmach testowych niż Zn(II). Ze względu na najwyższą czułość L. gibba jest najlepszym biomonitorem do oceny jakości środowiska naturalnego. Najmniejszą wrażliwość na Cr(VI) i Zn(II) wykazały odpowiednio L. minor i S. polyrhiza. Jest to prawdopodobnie spowodowane ich zdolnościami antyoksydacyjnymi i dlatego mogą być one najbardziej skuteczne w usuwaniu metali ze środowiska wodnego

Antyoksydanty a stres środowiskowy, badania spektralne stabilności substancji naturalnych i ich oddziaływanie z molekułą białka

The stability of eight hydroxycinnamic acids (HCAs) during long-term incubation under physiological conditions was studied by UV-VIS absorption spectroscopy and their possibility of binding to a model protein (bovine serum albumin, BSA) under physiological conditions was investigated by tryptophan fluorescence quenching method. The obtained results suggest that the stability of hydroxycinnamic acids is dependent upon its individual structure and duration of incubation. The monosubstituted derivatives (coumaric acids) were stable within the course of long-term incubation, while di- and trisubstituted derivatives decomposed easily. It was found out that all studied compounds changed fluorescence emission spectrum of BSA. The Stern-Volmer analysis was employed in order to explore binding of HCAs to BSA in details. The binding constants (Kb), number of binding sites (n) and the free energy changes (∆G0) were determined. The binding affinity was strongest for rosmarinic acid and ranked in the following order rosmarinic acid > chlorogenic acid > sinapic acid > caffeic acid > ferulic acid > o-coumaric acid > p-coumaric acid > m-coumaric acid. All free energy changes (∆G0) possessed negative sign indicating the spontaneity of HCAs binding to BSA.Badano trwałość ośmiu kwasów hydrooksycynamonowych, HCAs, podczas inkubacji długoterminowej w warunkach fizjologicznych i możliwość ich wiązania się z modelowym białkiem (albuminą, BSA). Uzyskane wyniki pokazały, że trwałość tych kwasów zależy od ich indywidualnej budowy oraz czasu inkubacji. Wyznaczono stałe trwałości (Kb), liczbę miejsc wiązania (n) oraz zmianę wartości energii Gibbsa (∆G0) wiązania HCAs do BSA, który to proces przebiegał samorzutnie

Green tea catechins can bind and modify ERp57/PDIA3 activity.

Background Green tea is a rich source of polyphenols, mainly catechins (flavanols), which significantly contribute to the beneficial health effects of green tea in the prevention and treatment of various diseases. In this study the effects of four green tea catechins on protein ERp57, also known as protein disulfide isomerase isoform A3 (PDIA3), have been investigated in an in vitro model. Methods The interaction of catechins with ERp57 was explored by fluorescence quenching and surface plasmon resonance techniques and their effect on ERp57 activities was investigated. Results A higher affinity was observed for galloylated cathechins, which bind close to the thioredoxin-like redox-sensitive active sites of the protein, with a preference for the oxidized form. The effects of these catechins on ERp57 properties were also investigated and a moderate inhibition of the reductase activity of ERp57 was observed as well as a strong inhibition of ERp57 DNA binding activity. Conclusions Considering the high affinity of galloylated catechins for ERp57 and their capability to inhibit ERp57 binding to other macromolecular ligands, some effects of catechins interaction with this protein on eukaryotic cells may be expected. General significance This study provides information to better understand the molecular mechanisms underlying the biological activities of catechins and to design new polyphenol-based ERp57-specific inhibitors