Margetić, Aleksandra

Vujčić, Zoran

FEBS Journal

Central Repository of the Institute of Chemistry, Technology and Metallurgy (CER)

tory activity produced by TRSase Ap3A, is to stimulate the syn-thesis of NO and start a cascade of regulatory anti-inflammatoryand antioxidant responses.SW02.S6–37Dinucleoside polyphosphates as key regulatorsof biological processes in tissues and body:molecular aspects of their synthesis byaminoacyl-tRNA synthetasesM. K. Nurbekov1, D. V. Yarygin1, N. O. Minkova1 and R. I.Zhdanov21Sholokhov Moscow State University for the Humanities, Moscow,Russia, 2Kazan Federal University, Kazan, RussiaDinucleoside polyphosphates (ApnA) have a large range of regu-latory functions at different levels of organisms, ranging from thehighest forms of multicellular till lower unicellular forms. Theimportance and universality of regulatory functions of the ApnAfollows from the known role of this metabolite in the formationof microbial biofilms in the implementation of adaptive featuresnamed ‘quorum sensing’ in communities of microorganisms. Act-ing as a second messenger as extracellular signaling molecules,ApnA can function as neurotransmitter regulators of blood flowas a vasoconstrictor and vasodilator, depending on the length ofthe phosphate chain. Ap3A, Ap4A activate or inhibit the develop-ment and the ability to aggregate platelets, stimulate the biosyn-thesis of DNA in cells. Based on our findings and the literaturedata, is well established that one of the main sources of theApnA in the body of higher organisms are aminoacyl-tRNA syn-thetases (ARSase), in particular, tryptophanyl-tRNA synthetase(TRSase). TRSase is involved in the synthesis of Ap3A, but notAp4A, due to the presence of discovered by us significant for cat-alytic activity zinc ion in the enzyme. The presence of a widerange of regulatory functions of TRSase which is synthesized pri-marily as apoenzyme, requires specific, well-functioning regula-tory mechanisms at the level of protein that can switch from thebasic canonical to additional, non-canonical activity. Highimportance of the non-canonical regulatory activity of the Ap3Asynthesised by TRSase confirms the involvement of these metab-olites in the startup stages of defense reactions in the body, inparticular the synthesis of nitrous oxide (NO) in the tissue, whichis one of the key regulators of homeostasis of the cardiovascularsystem.The studies revealed a subtle mechanism of interactions of dif-ferent types of covalent modification of the TRSase with sub-strates and intermediates of enzymatic reactions (Trp, PPi, ATP)and, in particular, with zinc for tissue-specific implementation ofthe non-canonical functions, including the controlled synthesis ofan important secondary messenger of cells and tissues – Ap3A.SW02.S6–38Thermal stability and energy of deactivation ofimmobilized cell wall invertase in natural andsynthetic hydrogel polymersA. Margetic1 and Z. Vujcic21Institute of Chemistry, Technology and Metallurgy, Centre ofChemistry, University of Belgrade, Belgrade, Serbia, 2Departmentof Biochemistry, Faculty of Chemistry, University of Belgrade,Belgrade, SerbiaThe greatest amount of invertase in the cell of yeast Saccharomy-ces cerevisiae is located in the cell wall. Enzyme immobilizationoffers technical and economic advantages. Industrial applicationsof immobilized biocatalysts have been gaining importance inrecent decades as they are widely used. Hydrogel materials areincreasingly studied for application in biological sensing, drugdelivery, tissues regeneration and food industry for number ofreasons.The aim of this work was comparison some of importantkinetic parameters for enzyme reaction of a cell wall invertaseimmobilized in a few hydrogel carriers. Enzyme was immobilizedin different natural (alginate and gelatin) and synthetic polymers(polyacrylamide). Concentration of enzyme in all immobilized bi-ocatalyst was the same. Differences in activity of obtained biocat-alyst were observed, while no significant difference in pH andtemperature optima, as well as in activation energy and Michael-is-Menten kinetics parameters were shown. Significant differencebetween these biocatalysts was observed in their thermal stability.Thermal stability of free and immobilized cell wall invertase wasdetermined by monitoring the enzyme activity at a few differenttemperatures between 50 and 70°C. Deactivation constants (kd)were calculated from Arrhenius equation for all biocatalysts (freeand immobilized) for various working temperatures. Obtained kdvalues are plotted in the form of Arrhenius plot, that is ln of kdagainst the inverse of absolute temperature, yielding the energyof deactivation, as the angular coefficient of the adjusted straightline, times the universal gas constant. The obtained values are326, 592, 620 and 706 kJ/mol for free, polyacrylamide, alginateand gelatin immobilized cell wall invertase, respectively. There-fore, increase of the energy of deactivation of immobilizedenzyme shown greater stability than free enzyme, but the greateststability was proven for enzyme immobilized in gelatin hydrogel.SW02.S6–39Immobilization of NAD+/NADH on magneticnanoparticles and its selective oxidation andreduction reactions with mediated bygalactitol- and lactate- dehydrogenasesB. Tural1, T. Tarhan2 and S. Tural11Department of Chemistry, Faculty of Education, Dicle University,Diyarbakir, Turkey, 2Department of Vocational High School ofHealth Services, Mardin Artuklu Universty, Mardin, TurkeyRedox reactions in biochemistry have an important function andthey are catalyzed by dehydrogenases and oxidoreductases. Thesereactions have large application by bio fuels, sensing technologyand biotransformation for the production of several interestingmaterials.The oxidoreductases are working with co-factors NAD+/NADH and their recycling are essential for economical reason.The recycling and reusability is a big challenge in bio fuel, sens-ing and biotransformation technologies. Without recycling theuse of oxidoreductases are more expensive than their products.Many attempts are made for the reusability these materials. Thesolution of this problem is in the same time the solution associ-ated with hydride (hydrogen) generation. This study focus on thesynthesis of NAD+/NADH functionalized Fe3O4 magnetic nano-particles and their application on the redox enzyme reactions fordeveloping a method which enable ease regeneration and reuse ofcofactors.First, silica coated magnetite particles were synthesized and 3-Aminophenyboronic acid (APBA) was attached on the surface ofparticles. Nicotinamide adenine dinucleotide (NAD) was immobi-lized on the magnetically responsive APBA attached magneticsupport. X-ray diffraction (XRD), Fourier transform infraredspectroscopy (FTIR), and transmission electron micrograph(TEM) methods were used to characterize the surface modifiedmagnetic nanoparticles.FEBS Journal 280 (Suppl. 1) (2013) 3–617ª 2013 The Authors. FEBS Journal ª 2013 FEBS 103SW02 Biocatalytic Mechanisms and Protein Dynamics Abstracts

Thermal stability and energy of deactivation of immobilized cell wall invertase in natural and synthetic hydrogel polymers

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Thermal stability and energy of deactivation of immobilized cell wall invertase in natural and synthetic hydrogel polymers

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