Effect of water solvation on the heat effects of dehydration of alpha-chymotrypsin in organic solvents

© 2014 by Nova Science Publishers, Inc. All rights reserved. Enthalpy changes on the interaction of the dried and hydrated bovine pancreatic α-chymotrypsin (CT) with anhydrous organic solvents (dimethyl sulfoxide (DMSO), formamide, ethylene glycol, and methanol) were measured by isothermal calorimetry at 25°C. Initial hydration level of CT was varied in a wide range of water content (from 0 to 0.3 g water/g enzyme). The interaction enthalpies of the dried CT with anhydrous organic solvents are exothermic. At high water content (more than 0.2 g water/g enzyme), the interaction enthalpies are endothermic for formamide and exothermic for DMSO, methanol, and ethylene glycol. These thermochemical data were analyzed to calculate the molar enthalpies of dehydration of the enzymes in organic liquids. The dehydration enthalpy changes may be endothermic or exothermic depending on the initial water content and the water solvation enthalpy value. The most important conclusions can be described as follows: (i) The solvation of water by hydrophilic organic solvent determines the changes in the dehydration enthalpy values; (ii) The data for the enthalpies of solvation of water by the solvent at infinite dilution reflect this effect

A network-based structure-preserving dynamical model for the study of cascading failures in power grids

In this work we show that simple classic models of power grids, albeit frequently utilized in many applications, may not be reliable for investigating cascading failures problems. For this purpose, we develop a novel model, based on a structure-preserving approach, to obtain a network-based description of a power grid, where nodes correspond to generators and buses, while the links correspond to the physical lines connecting them. In addition, we also consider classic voltage and frequency protection mechanisms for lines and buses. Considering the Italian power grid as a case study of interest, we then investigate the propagation of an initial failure of any line of the power system, and compare the predicted impact of the failure according to different assumptions in the model such as the presence or absence of protection mechanisms and a simplified description of the system dynamics. In particular, it can be observed that more realistic models are crucial to determine the size of the cascading failure, as well as the sequence of links that may be involved in the cascade

A study of the hydration of lysozyme in neat organic solvents using isothermal calorimetry: Effect of water solvation

© 2015 Elsevier B.V. Abstract The interaction enthalpies of the dried and hydrated lysozyme with neat organic solvents (DMSO, formamide, ethylene glycol, and methanol) were obtained at 25°C. These organic solvents represent a series of liquids in which the water solvation enthalpy is gradually changed over a wide range. The interaction enthalpies of the dried lysozyme with neat organic solvents are exothermic. At high water content, the interaction enthalpies are endothermic for formamide and exothermic for DMSO, methanol, and ethylene glycol. The dehydration enthalpies of lysozyme in organic liquids may be endothermic or exothermic depending on the initial water content and the water solvation enthalpy

Balnase, a New Dimer-Forming Ribonuclease from Bacillus altitudinis

© 2016, Springer Science+Business Media New York.Current cancer treatments still remain ineffective and cause side effects which ruinously affect healthy cells. Among new promising anticancer drugs, special attention is paid to the ribonucleases (RNases) which possess selective cytotoxicity against malignant cells. It is found that besides enzymatic activity conformational state of RNase molecules plays a role in the anticancer activity. Balnase, a new RNase from Bacillus altitudinis, is a close homolog of Bacillus pumilus RNase (binase) which selectively kills malignant cells expressing oncogenes KIT, ras, AML1/ETO, and FLT3. Earlier, homogeneous sample of balnase was obtained. Here, we have characterized structural organization of balnase. It was shown that it is a natural dimer. The enzyme has the same conformational state as binase but balnase dimers are less stable

Heat effects of dehydration of human serum albuminin hydrophilic organic solvents

A thermochemical model for describing the transfer of water from the protein phase to the organic solvent liquid phase and for determining how the solvation ability of organic solvents affects this process was developed. Enthalpy changes on the interaction of dried and hydrated human serum albumin (HSA) with hydrophilic organic solvents (dimethyl sulfoxide, formamide, ethanol, methanol and acetic acid) and water were measured by isothermal calorimetry at 25°C. The initial hydration level of human serum albumin was varied in the entire water content range from 0-30% g water/g HSA. The dependence of the interaction enthalpies on the initial water content is complex. The interaction enthalpies of the dried HSA with organic solvents are exothermic. At low water contents (less than 0.1 g/g), there is a sharp increase in the interaction enthalpy values. At the highest water contents (more than 0.2 g/g), the interaction enthalpies are endothermic for acetic acid and formamide and exothermic for DMSO, methanol, and ethanol. These thermochemical data were analyzed in conjunction with the results for the water adsorption in organic solvents to calculate the molar enthalpies of dehydration of HSA in organic liquids. It was found that the dehydration enthalpy changes may be endothermic or exothermic depending on the initial water content and the water solvation enthalpy value. From the results obtained, it can be concluded that: (i) only the solvation of water by hydrophilic organic solvent determines the changes in the dehydration enthalpy values, and (ii) the data for the enthalpies of solvation of water by the solvent at infinite dilution reflect this effect. © Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

ПРИНЦИПИ ІНФЕКЦІЙНОГО КОНТРОЛЮ В МЕДСЕСТРИНСЬКІЙ ПРАКТИЦІ

In the article the modern approaches to the implementation of infection control measures in hospitals to prevent nosocomial infections were analyzed; we have specified the essential components of programs that provide better control of nosocomial infections and are adapted to the conditions of specific health care setting.У статті проаналізовано сучасні підходи до впровадження заходів інфекційного контролю у лікарняних закладах з метою профілактики внутрішньолікарняних інфекцій, вказано необхідні складові програм, які забезпечуватимуть кращий контроль внутрішньолікарняних інфекцій та будуть адаптованими до умов конкретного лікарняного закладу

Balnase, a New Dimer-Forming Ribonuclease from Bacillus altitudinis

© 2016, Springer Science+Business Media New York.Current cancer treatments still remain ineffective and cause side effects which ruinously affect healthy cells. Among new promising anticancer drugs, special attention is paid to the ribonucleases (RNases) which possess selective cytotoxicity against malignant cells. It is found that besides enzymatic activity conformational state of RNase molecules plays a role in the anticancer activity. Balnase, a new RNase from Bacillus altitudinis, is a close homolog of Bacillus pumilus RNase (binase) which selectively kills malignant cells expressing oncogenes KIT, ras, AML1/ETO, and FLT3. Earlier, homogeneous sample of balnase was obtained. Here, we have characterized structural organization of balnase. It was shown that it is a natural dimer. The enzyme has the same conformational state as binase but balnase dimers are less stable

Kemeny-based testing for COVID-19

Testing, tracking and tracing abilities have been identified as pivotal in helping countries to safely reopen activities after the first wave of the COVID-19 virus. Contact tracing apps give the unprecedented possibility to reconstruct graphs of daily contacts, so the question is: who should be tested? As human contact networks are known to exhibit community structure, in this paper we show that the Kemeny constant of a graph can be used to identify and analyze bridges between communities in a graph. Our 'Kemeny indicator' is the value of the Kemeny constant in the new graph that is obtained when a node is removed from the original graph. We show that testing individuals who are associated with large values of the Kemeny indicator can help in efficiently intercepting new virus outbreaks, when they are still in their early stage. Extensive simulations provide promising results in early identification and in blocking the possible 'super-spreaders' links that transmit disease between different communities

The higher level of organization of the oxidative phosphorylation system: mitochondrial supercomplexes

The organization of the oxidative phosphorylation (OXPHOS) system within the inner mitochondrial membrane appears to be far more complicated than previously thought. In particular, the individual protein complexes of the OXPHOS system (complexes I to V) were found to specifically interact forming defined supramolecular structures. Blue-native polyacrylamide gel electrophoresis and single particle electron microscopy proved to be especially valuable in studying the so-called “respiratory supercomplexes”? Based on these procedures, increasing evidence was presented supporting a “solid state” organization of the OXPHOS system. Here, we summarize results on the formation, organisation and function of the various types of mitochondrial OXPHOS supercomplexes

Исследование олеогеля на основе компонентов Helianthus annuus L. и Rosmarinus officinalis L. в качестве фритюрного жира

The aim of this study was to study the oxidation resistance and functional properties of oleogels based on high oleic oil and wax from Helianthus annuus L. with the addition of a natural complex antioxidant — an extract from Rosmarinus officinalis L. and lecithin from Helianthus annuus L. — when used as a frying medium for French-fries. High oleic sunflower oil was structured into an oleogel with sunflower wax at a dosage of 5%. Studies were carried out to determine the possibility of replacing the synthetic antioxidant tert-butylhydroquinone at a dosage of 200 mg/kg with a natural antioxidant based on rosemary extract and sunflower lecithin in an oleogel with a defoamer. It was determined that the introduction of sunflower wax increased the induction period of high-oleic sunflower oil by 1.6 times, and the additional introduction of defoamer and antioxidants increased this figure by 1.8–2 times. The rate of accumulation of oxidation products in oil, which is characterized by the level of total polar materials, decreased when wax and antioxidants were added. The degree of thermal oxidation most quickly reached the limit value in oil without additives; in oleogels, it significantly decreased. The introduction of sunflower wax into oil contributed to a noticeable decrease in the absorption of oil by potatoes: fried in oleogel, it absorbed 34–38% less oil than fried in oil without additives. The addition of 0.07% rosemary extract with sunflower lecithin to the oleogel increased the operating time of frying oil by at least 2 times, approximately the same as that of the oleogel with tert-butylhydroquinone. This makes it possible to replace the synthetic antioxidant in deepfrying oleogel with natural rosemary extract with sunflower lecithin. The developed oleogel is a frying oil that has a longer service life and allows you to get fried products with a lower amount of fat.Целью настоящего исследования являлось изучение устойчивости к окислению и функциональных свойств олеогелей на основе высокоолеинового масла и воска из Helianthus annuus L. с вводом натурального комплексного антиокислителя — экстракта из Rosmarinus officinalis L. и лецитина из Helianthus annuus L. — при использовании их в качестве жарочной среды для картофеля-фри. Высокоолеиновое подсолнечное масло было структурировано в олеогель подсолнечным воском в дозировке 5%. Проводили исследования по определению возможности замены синтетического антиокислителя трет-бутилгидрохинона в дозировке 200 мг/кг на натуральный антиокислитель на основе экстракта розмарина и подсолнечного лецитина в олеогеле с пеногасителем. Было определено, что внесение подсолнечного воска увеличило индукционный период высокоолеинового подсолнечного масла в 1.6 раза, а дополнительный ввод пеногасителя и антиокислителей увеличил данный показатель уже в 1.8–2 раза. Скорость накопления продуктов окисления в масле, характеризующаяся уровнем общих полярных веществ, при внесении воска и антиокислителей снижалась. Степень термического окисления быстрее всех достигла предельного значения в масле без добавок, в олеогелях она заметно снижалась. Введение в масло подсолнечного воска способствовало заметному снижению впитываемости масла картофелем: обжаренный в олеогеле, он впитывал на 34–38% меньше масла, чем обжаренный в масле без добавок. Внесение в олеогель 0.07% экстракта розмарина с подсолнечным лецитином увеличивало время эксплуатации фритюрного жира не менее чем в 2 раза примерно также, как и у олеогеля с трет-бутилгидрохиноном. Это дает возможность произвести замену синтетического антиокислителя в олеогеле для фритюра на натуральный экстракт розмарина с подсолнечным лецитином. Разработанный олеогель является фритюрным жиром, имеющим более длительный срок эксплуатации и позволяющим получать обжаренные продукты с более низким количеством жира