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Overview of the evolutionary history and the role in citric acid production of alternative oxidase
Published March 20, 2013
83-88

...5); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">All organisms are exposed to countless environmental effects, which influence in a disadvantageous way their life processes. They continuously adapt to the changing conditions and respond to the stress impacts by defence mechanisms. Through different signal transduction pathways they are able to increase or decrease the expression of their genes and consequently modify their metabolic processes. My interest focuses on alternative oxidase (AOX) enzyme whose expression is often increased under biotic and abiotic stress. The so far proven and putative functions of the AOX play a role in the ability of organisms to adapt to different conditions, such as heavy metals accumulation, pathogenic infection, oxidative stress and lack of oxygen or nutrients.

AOX is a member of the di-iron carboxylate protein family. Members of the di-iron carboxylate protein family are present in all kingdoms of life. They are considered to have ancient origin. It is believed that their sulfide-resistant and oxygen-reducing ability played a role in the survival of organisms during the transition between the anaerobic and the aerobic world. It is assumed that the AOX arose in eukaryotes through a primary endosymbiotic event, and this event made possible the development of mitochondria. Afterwords, vertical inheritance, and secondary and tertiary endosimbiotic events led to its spread among eukaryotes. It is assumed that bacteria obtained AOX by horizontal gene transfer from plants.

AOX-catalyzed alternative respiration plays an important role in the operation of energy-producing and biosynthesizing system of microorganisms. In these cases, the regeneration of reduced cofactors is an essential condition, and therefore may be rate-limiting for biotechnological processes, including the citric acid production.

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The significance of sour cherry in iron supplementation
Published February 17, 2015
101-104

The iron concentration of ’Csengődi csokros’, ’Debreceni- and ’Érdi bőtermő’ , ‘Éva’, ’Kántorjánosi’ ,’Petri’ and the ’Újfehértói fürtös’ cultivars was determined by ICP-MS. Furthermore the Vitamin C, L-Malis acid and Citric acid concentration of samples were measured.

Our results show that large am...ount Fe2+ (average 20.5 mg kg-1) accumulates in the pulp of sour cherry. Besides, the concentration of Vitamin C, L-Malis acid, that increase the absorption of iron, are high. Based on these results, the sour cherry and the products of sour cherry play an important role in the forming of iron content in body.

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Selenium speciation analysis of selenium-enriched food sprouts
Published March 11, 2014
23-28

In this present study, we prepared selenium-enriched pea and wheat sprouts. During our research we aimed not only to measure the total selenium content of the sprouts but to identify different selenium species.

Scientifical researches show why the analytical examination of different selenium (Se) species is necessary: consumption of all... kind of Se-species is useful for a person who suffers in selenium deficit, while there is significant difference between effects of different Se-species on person, in whose body the Se-level is just satisfactory. Biological availability, capitalization, accumulation, toxicity of Se-species are different, but the main difference was manifested in the anti-cancer effect of selenium.

During our research selenium was used in form of sodium selenite and sodium selenate, the concentration of the solutions used for germination was 10 mg dm-3. Control treatment meant germination in distilled water. Total selenium content of sprout samples was measured after microwave digestion by inductively coupled plasma mass spectrometry (ICP-MS). Different extraction solvents were applied during sample preparation in order to separate different Se-species (0.1 M and 0.2 M HCl or 10 mM citric acid buffer). We wanted the following question to be answered: Which extraction solvent resulted the best extraction efficiency? Selenium speciation analysis of sprout sample extracts was performed by high performance liquid chromatography with anion exchange column, detection of selenium species was performed by ICP-MS.

Evaluating our experimental results we have been found that significant amount of selenium of inorganic forms used during germination transformed into organic selenium compounds. There was difference between the amount of Se-species in pea and wheat sprouts and selenium uptake and repartition of selenium species were depended on Se-form used during germination. In addition the chromatogram analysis made us clear as well, that the citric acid solvent proved to be the most effective extraction solvent during sample preparation int he view of organic Se species.

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