Lipaze katalizuojamos reakcijos kinetikos kompiuterinis modeliavimas

The kinetics of lipase catalyzed reaction (hydrolysisof ascorbic acid palmitate), described by the system of simple non-linear differential equations was presented. The system was solved analytically and the result expressed by formula. With reference to calculated solution the current dependence on various parameters was performed. The comparison of experiments [3] and calculated results was made.Straipsnyje nagrinėjama paprastų netiesinių diferencialinių lygčių  sistema, kuri aprašo lipaze katalizuojamos askorbo rūgšties palmitato hidrolizės kinetiką. Ši sistema buvo sprendžiama analitiškai ir gautas sistemos sprendinys formulių pavidalu. Remiantis apskaičiuotu sprendiniu buvo ištirta pradinio srovės augimo greičio priklausomybė nuo įvairių parametrų.  Palyginti eksperimentiniai [3] ir modeliavimo rezultatai

Glucose sensor based on nanostructured carbon electrode with immobilized PQQ-containing glucose dehydrogenase: Construction, experimental study and mathematical modeling

Oxidized graphite (OG) has been prepared by carrying out the synthesis of graphene in the alkaline media using K3[Fe(CN)6] as the oxidizing agent. This synthesis protocol allowed us to obtain and further to apply the OG as an effective electrode material for the reagentless enzyme electrode in which electron transfer between electrode and enzyme active site proceeds directly, without any additional mediators. Direct electron transfer in this bioelectrocatalytic system has been achieved from the active site of pyrroloquinoline quinone-containing glucose dehydrogenase (PQQ-GDH) to the nanostructurized carbon electrode surface. The numerical modeling of biosensor made possible to determine several structural and kinetic parameters of the sensor constructed. Our model of PQQ-GDH-based biosensor is built under three main assumptions. First, we assume that the electron transfer between enzyme active center and OG proceeds via the electron hopping mechanism, and therefore the rate of this reaction depends on the diffusion coefficient of an electron in OG layer. Second, enzyme is immobilized, and its diffusion coefficient is assumed to be zero. Finally, after the reaction with substrate, enzyme needs to be regenerated by the oxidized functionalities of OG

Sveikiname jubiliatę - Lietuvos mokslų akademijos viceprezidentę akademikę profesorę habilituotą daktarę - Veroniką Vasiliauskienę

Vytauto Didžiojo universitetasŽemės ūkio akademij

Interfacial behavior of ferrocene- and 1,4-naphthoquinone-based compounds, and their mixtures with monoolein at the air/water interface

In this work, a Study of the interfacial properties of redox-active novel ferrocene- and 1,4-naphthoquinone-based compounds containing an alkenyl chain is presented. The miscibility of these corn. pounds with 1-monooleoylglycerol (monoolein, MO), a well-known and much studied substance because of its rich polyinorphism in water, at the air/water interfaces was investigated by using the Langmuir surface film balance to get a better understanding of the interaction between MO and the new derivatives. The influence of temperature on the monolayer structure was also studied. It has been demonstrated that the monolayers of all compounds have a liquid-expanded structure. and that the mixed films are more stable compared to the layers of the individual compounds

Computational Modeling of the Electrochemical System of Lipase Activity Detection

sensor

Horse heart cytochrome c entrapped into the hydrated liquid-crystalline phases of phytantriol: X-ray diffraction and Raman spectroscopic characterization

Small angle X-ray diffraction (SAXD), resonance Raman (RR) spectroscopy with 413 nm excitation, and non-resonance Raman technique with 785 nm excitation were used to probe the influence of entrapped cytochrome c (Cyt c) on the structure of hydrated phytantriol (Phyt) liquid-crystalline phases as well as conformational changes of heme group and secondary structure of the protein. SAXD measurements indicated that incorporation of Cyt c affects both nanostructure dimensions and type of liquid-crystalline phases of hydrated Phyt. The unit cell dimensions decrease with increasing Cyt c concentration for all phases. In addition, protein perturbs the nanostructure of Q(230) and Q(224) liquid-crystalline phases of hydrated Phyt to such an extent that they transform into the Q(229) phase with the Im3m space group. RR data revealed that entrapment of oxidized Cyt c into the Q(230) phase at 1 wt.% content results in near complete reduction of central iron ion of the heme group, while its low-spin state and six-ligand coordination configuration are preserved. Based on the analysis of heme out-of-plane folding vibration near 568 cm(-1) (gamma(21)) and nu(48) mode at 633 cm(-1), it was demonstrated that the protein matrix tension on the heme group is relaxed upon incorporation of protein into Q(230) phase. Non-resonant Raman bands of difference spectra showed the preservation of alpha-helix secondary structure of Cyt c in the liquid-crystalline phase at relatively high (5 wt.%) content. The Cyt c induced spectroscopic changes of Phyt bands were found to be similar as decrease in temperature. (C) 2012 Elsevier Inc. All rights reserved

Enzyme encapsulation in nanostructured self-assembled structures: Toward biofunctional supramolecular assemblies

Enzymes have come into use for many new applications outside their natural biological environment, taking advantage of their high efficiency and selectivity as biocatalysts. Such new application often requires encapsulation to preserve the structure and activity of the enzyme, but also to regulate and control the activity. Here, we will discuss two types of encapsulation, soft matrices consisting of polar lipid liquid crystals and hard ordered mesoporous silica matrices. For both types of matrices, the challenge is to control the pore size of the matrices and the interaction with the matrix interface. Here, the polar lipid liquid crystals offer larger flexibility than silica, but on the other hand, it is considerably more sensitive to the environment