Na+/K+-atpase - activity and inhibition

The aim of the study was to give an overview of the mechanism of inhibition of Na+/K+-ATPase activity. For this purpose, the effect of ouabain like compounds (digoxin, gitoxin), platinum group complexes ([PdCl4]2-, [PdCl(dien)]+ and [PdCl(Me4dien)]+), transition metal ions (Cu2+, Zn2+, Fe2+, Co2+) and heavy metal ions (Hg2+, Pb2+, Cd2+) on the activity of Na+/K+-ATPase isolated from rat synaptic plasma membranes (SPM), cortex of pig and human erythrocytes and was investigated.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Stabilization of D-Amino Acid Oxidase via Covalent Immobilization and Mathematical Model of D-Methionine Oxidative Deamination Catalyzed by Immobilized Enzyme

Porcine kidney D-amino acid oxidase was stabilized by covalent immobilization on spherical particles of Eupergit C because of its low stability in soluble form. The focus of this work was to evaluate operational stability of the immobilized enzyme. To evaluate D-amino acid oxidase’s operational stability during process conditions, repetitive batch reactor experiments of D-methionine oxidation reaction were carried out with continuous aeration for oxygen supply at air-flow rates of 5 and 10 dm3 h–1. Kinetic analysis of the immobilized enzyme was done as well. The mathematical model of D-methionine oxidative deamination catalyzed by the immobilized D-amino acid oxidase was developed and it described the data well. It enabled the estimation of operational stability decay rate constant. It was possible to achieve 100 % substrate conversion in all batch experiments

Retrobulbar chondrosarcoma in a dog

This paper presents a review of a dog, with a retrobulbar chondrosarcoma, which was admitted for surgery for visible changes in his eye during inspection. Orbital neoplasia in dogs may be primary and secondary. Sixty percent of orbital neoplasia in dogs are primary, ninety percent of which are malignant. Retrobulbar neoplasms are rare and in their early stage represent a diagnostic challenge. Chondrosarcoma of the skull is a slow-progressing malignant disease which occurs locally, aggressive with invasion into the surrounding tissues. Dogs with chondrosarcoma of the skull have life expectancy between 210 and 580 days - in our case it was 180 days - after the first alterations on the eye of the dog occurred

Modelling and Optimization of the (R)-(+)-3,4-dihydroxyphenyllactic Acid Production Catalyzed with D-lactate Dehydrogenase from Lactobacillus leishmannii Using Genetic Algorithm

A mathematical model for the enzymatic kinetics of the synthesis of (R)–(+)–3,4-dihydroxyphenyllactic acid (DHPL) was developed. The synthesis was catalyzed by D-lactate dehydrogenase from Lactobacillus leishmannii. Since this enzyme requires NADH as a coenzyme, formate dehydrogenase system was used for NADH regeneration. Kinetic constants of both enzymes were estimated independently from initial reaction rate experiments. The developed mathematical model was verified by the batch reactor experiment (volumetric productivity in this experiment was 4.76 g dm–3 d–1). Optimization of initial reaction conditions for DHPL synthesis was performed using the genetic algorithm (GA). The genetic algorithm as a flexible optimization tool had been used to obtain the experimental conditions where maximal volumetric productivity could be achieved. The optimal initial conditions were found in the investigated parameter area: c3,4-dihydroxyphenylpyruvic acid = 4.69 mmol dm–3, cNAD+= 4.95 mmol dm–3, cformate = 36.85 mmol dm–3, D-lactate dehydrogenase = 3 mg cm–3, formate dehydrogenase = 2.94mg cm–3 and the reaction time 8.5 min. At these conditions volumetric productivity of 93.06 g dm–3 d–1 can be achieved

Thermal Stability and Phase Transformations of Multicomponent Iron-Based Amorphous Alloys

Due to their excellent functional properties enabling their applicability in different fields of modern technology, amorphous alloys (metallic glasses) based on iron have been attracting attention of many scientists. In this chapter, the results of multidisciplinary research of five multicomponent iron-based amorphous alloys with different chemical composition, Fe81Si4B13C2, Fe79.8Ni1.5Si5.2B13C0.5, Fe75Ni2Si8B13C2, Fe73.5Cu1Nb3Si15.5B7, and Fe40Ni40P14B6, are summarized in order to study the influence of chemical composition on their physicochemical properties and functionality. The research involved thermal stability, mechanism, thermodynamics, and kinetics of microstructural transformations induced by thermal treatment and their influence on functional properties. Determination of crystallization kinetic triplets of individual phases formed in the alloys is also included. The results obtained for different alloys are compared, correlated, and discussed in terms of the alloy composition and microstructure

Inhibition of myeloperoxidase by quercetin

Reaction mechanism of quercetin induced inhibition of myeloperoxidase isolated from human neutrophils was proposed by following peroxidase activity of the enzyme, using the o-dianisidine and H2O2 as substrates. The dependence of initial reaction rate vs. H2O2 concentration in the absence and presence of quercetin revealed the reaction mechanism that involved the enzyme inhibition by the excess of the substrate. The rate and equililbria constants for proposed reaction paths were determinedPhysical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200

Current-voltage characteristics of carbon nanotube FETS

U ovom radu ispitivane su karakteristike FETova izrađenih na bazi ugljeničnih nanotuba (CNT FETova). U prvom delu rada, predstavljene su neke osnovne osobine ugljeničnih nanotuba. Zatim je razvijen analitički model strujno-naponskih karakteristika CNT FETova koji dobro opisuje ponašanje ove savremene nanoelektronske naprave. Na bazi predloženog modela urađene su simulacije. Dobijeni rezultati su u saglasnosti sa prethodno publikovanim. .In this paper, one of the most actual devices - carbon nanotube field effect transistor (CNT FET) is investigated. At the beginning, the nanotube properties are presented. The main contribution of this paper is the new analytical model of CNT FET current-voltage characteristics. Developed model describes behavior of CNT FET in very good manner and, at the same time, the model is relatively simple. Using the developed model, simulations were performed. The results obtained by using proposed model are in very good agreement with already known and published ones.