Development of a novel electrochemical method for the detection of invertase enzyme in honey samples

Invertase (α-glucosidase) is one of the most important honey enzymes; it hydrolyses sucrose into fructose and glucose during honey ripening process. Next to the basic honey ingredients (glucose, fructose, water), invertase activity is one of the main characterising parameter of honey: it can be used as indicator of aging and/or overheating, but it also may give information about adulteration. Our aim was to develop a novel analytical method for the fast determination of invertase activity that can be used during quality control of honey samples. Our assay based on the application of an artificial substrate, namely p-nitrophenyl-α-D-glucopyranoside. p-Nitrophenol produced by the enzyme reaction is detected by amperometric method which is much more sensitive than the traditional spectrophotometric determination. Screen-printed carbon electrodes and a potentiostat were used for amperometric measurement. Our measuring system worked in flow injection system. The measuring parameters (polarization potential, pH etc.) were optimized. The applicability of the method was tested for detection of α-glucosidase enzyme activity

Új, funkcionalizált peptidszármazékok előállítása és oldategyensúlyi vizsgálata = Synthesis and solution equilibrium studies of new, functionalised derivatives of peptides

A pályázat keretében 15 új peptidhidroxámsavat állítottunk elő és szisztematikusan megvizsgáltuk azt, hogy a ligandumok építőelemeinek (terminális aminocsoport jelenléte, a hidroxámsavcsoport nitrogénjének szubsztituense, a peptidlánc hossza, az oldalláncban jelenlevő erősen koordinálódni képes donorcsoport jelenléte) megváltoztatása hogyan befolyásolja fémionmegkötő képességüket. A ligandumok esszenciális (Fe3+, Cu2+, Ni2+, Zn2+, Mo(VI)) és toxikus (Al3+) fémionokkal való kölcsönhatásának tanulmányozására pH-potenciometriát, ESI-MS-t és spektrális módszereket (UV-VIS, NMR, CD, ESR) alkalmaztunk, meghatározva az oldatbeli részecskék összetételét, stabilitási szorzat értékeit és legvalószínűbb oldatszerkezetét. | Fifteen new peptide hydroxamic acids have been synthesized, characterized and a systematic study has been carried out to explore the effect of the change of the building blocks (presence of the terminal amino group, substituent at the nitrogen of the hydroxamic moiety, length of the peptide chain, presence of strongly coordinating donor in the side chain) of the ligands on their metal binding capability. The interaction of the peptide hydroxamic acids with essencial (Fe3+, Cu2+, Ni2+, Zn2+, Mo(VI)) and toxic (Al3+) metal ions has been studied using pH-potentiometry, ESI-MS and different spectroscopic (UV-VIS, NMR, CD, ESR) techniques

Development of a novel electrochemical method for the detection of invertase enzyme in honey samples

Invertase (α-glucosidase) is one of the most important honey enzymes; it hydrolyses sucrose into fructose and glucose during honey ripening process. Next to the basic honey ingredients (glucose, fructose, water), invertase activity is one of the main characterising parameter of honey: it can be used as indicator of aging and/or overheating, but it also may give information about adulteration.   Our aim was to develop a novel analytical method for the fast determination of invertase activity that can be used during quality control of honey samples. Our assay based on the application of an artificial substrate, namely p-nitrophenyl-α-D-glucopyranoside. p-Nitrophenol produced by the enzyme reaction is detected by amperometric method which is much more sensitive than the traditional spectrophotometric determination.  Screen-printed carbon electrodes and a potentiostat were used for amperometric measurement. Our measuring system worked in flow injection system. The measuring parameters (polarization potential, pH etc.) were optimized. The applicability of the method was tested for detection of α-glucosidase enzyme activity

Élelmiszerek biogén amin tartalmának meghatározása HPLC technikával

Biogenic amines are important nitrogen-containing compounds of high biological importance in vegetable, microbial and animal cells. Although they are essential to living organisms, consumption of food containing high amounts of them may have toxicological effects. High amounts of certain amines may be found in food as a consequence of poor quality raw materials, contamination and inappropriate conditions during food processing and storage. Therefore biogenic amine, especially putrescine, cadaverine and histamine content in food can be consider as a freshness marker and could be used as an indicator of microbial spoilage. The aim of our work is to develop an HPLC method for quantitative determination of biogenic amines in food products. The chromatographic separation was carried out on a C18 column using a water acetonitrile elution gradient. UVdetection at 254 nm could be used after pre-column derivatisation with dansylchloride. In case of wines and beers determination can be done without any other sample pre-treatment, while the amine content of solid food samples need to be extracted with acid aqueous solution. 0.4 M HClO4, 5% trichloroacetic acid (TCA), 0.1 M HCl solutions and phosphate buffer pH=7 were tested as extraction solution, and then 0.4 M HClO4 was selected. The method was applied for analysis of different wine, beer, cheese, meat, sausages and fish samples. The detected levels of biogenic amines are below the amounts considered to have an adverse effect on human health

Investigation of metal complexes of peptides containing thioether and imidazole groups

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DEVELOPMENT OF A NOVEL ELECTROCHEMICAL METHOD FOR THE DETECTION OF INVERTASE ENZYME IN HONEY SAMPLES

Invertase (α-glucosidase) is one of the most important honey enzymes; it hydrolyses sucrose into fructose and glucose during honey ripening process. Next to the basic honey ingredients (glucose, fructose, water), invertase activity is one of the main characterising parameter of honey: it can be used as indicator of aging and/or overheating, but it also may give information about adulteration. Our aim was to develop a novel analytical method for the fast determination of invertase activity that can be used during quality control of honey samples. Our assay based on the application of an artificial substrate, namely p-nitrophenyl-α-D-glucopyranoside. p-Nitrophenol produced by the enzyme reaction is detected by amperometric method which is much more sensitive than the traditional spectrophotometric determination. Screen-printed carbon electrodes and a potentiostat were used for amperometric measurement. Our measuring system worked in flow injection system. The measuring parameters (polarization potential, pH etc.) were optimized. The applicability of the method was tested for detection of α-glucosidase enzyme activity

Solution equilibria and structural characterisation of the palladium(II) and mixed metal complexes of peptides containing methionyl residues

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Copper(II) and zinc(II) complexes of the peptides Ac-HisValHis-NH 2 and Ac-HisValGlyAsp-NH2 related to the active site of the enzyme CuZnSOD

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