54 research outputs found
A természet szénhidrátkémikusai: enzimatikus glikozilezések = Nature's carbohydrate chemists: enzymatic glycosylation
Oligoszacharidok enzimekkel törtĂ©nĹ‘ előállĂtása egy igen vonzĂł alternatĂv mĂłdszer a konvencionális kĂ©miai megközelĂtĂ©s mellett, mert vĂ©dĹ‘ csoportok használata nĂ©lkĂĽl a cĂ©lvegyĂĽlet kĂ©pzĹ‘dĂ©sĂ©t eredmĂ©nyezi. Ezen pályázatban az anomer konfiguráciĂłt megtartĂł alpha amilázok transzglikozilezĂ©si kĂ©pessĂ©gĂ©t tanulmányoztuk humán amiláz szubsztrátok Ă©s inhibitorok előállĂtására. Az akarviozinil-izomaltozil- spiro-tiohidantoin szintĂ©zisĂ©t a Bacillus stearothermophilus maltogĂ©n amilázával (BSMA) oldottuk meg. A BSMA enzim az akarbĂłz pszeudotriszacharid rĂ©szĂ©t a glĂĽko-spiro-tiohodantoin (GTH) akceptorra transzferálta. A PTS-GTH szerkezetvizsgálata azt mutatta, hogy a glikozilezĂ©s fĹ‘kĂ©nt a glĂĽkĂłz 6-os OH-ján törtĂ©nt az anomer konfiguráciĂł megtartásával. Az akarbĂłzzal meghoszabbĂtott termĂ©k több nagyságrenddel hatĂ©konyabb inhibitora a humán amiláznak, mint a kis mĂ©retű GTH molekula. A humán amiláz nem rendelkezik transzferáz aktivitással, de mutáciĂłval sikerĂĽlt transzglikozilezĂ©si kĂ©pessĂ©get ?bevezetni? a vad tĂpusĂş enzimbe. A Tyr151Met mutánssal kromoforral jelzett maltooligoszacharidokat állĂtottunk elĹ‘ Ă©s a PNP 1-tio-bĂ©ta-maltooligoszacharidokat DP 2-4 izoláltuk. A Tyr151Met mutáns maltotetraĂłz donorrĂłl maltĂłz Ă©s maltotriĂłz egysĂ©geket transzferált kĂĽlönbözĹ‘ PNP glikozidokra. Az NMR analĂzisek szerint a mutáns enzim megĹ‘rĂzte sztereo-Ă©s regioszelektivitását. A glikozilezĂ©s a glikozil akceptor 4-es OH-ján törtĂ©nt.Jelenleg árpa amiláz mutánsokkal törtĂ©nĹ‘ szintĂ©zisek folynak. | Enzyme-catalyzed synthesis of oligosaccharides allows the formation of well-defined oligosaccharides selectively without using any protection of hydroxyl groups. In this project the application of transglycosylation ability of retaining glycosidases was studied for the synthesis of oligosaccharide substrates and inhibitors of human amylases. Synthesis of acarviosinyl-isomaltosyl-spiro-thiohydantoin has been achieved by Bacillus stearothermophilus maltogenic amylase (BSMA). BSMA was capable of transferring the acarviosine-glucose residue from an acarbose donor onto glucopyranosylidene-spiro-thiohydantoin (GTH). Structural studies revealed that the enzyme reserved its stereoselectivity. Glycosylation took place mainly at C-6 position. The isolated compound was found to be a much more efficient salivary amylase inhibitor than GTH with kinetic constants of KEI=0.19 uM and KESI= 0.24 uM. Transglycosylation activity has been introduced into human salivary alpha amylase by genetic engineering. Synthesis of PNP 1-thio beta-maltooligosaccharides DP 2-4 has been carried out by a Tyr151Met mutant of HSA. Tyr151Met was capable of transferring maltose and maltotriose residues from a maltotetraose donor onto different PNP glycosides. NMR studies revealed that the mutated enzyme preserved the stereo- and regioselectivity. The glycosylation took place at position 4 of the glycosyl acceptor, exclusively. Nowadays transferase activity of barley amylase mutants has also been studied
A nanoszelĂ©n kiegĂ©szĂtĂ©s hatása a vörös árnyĂ©khal (Sciaenops ocellatus) termelĂ©si paramĂ©tereire Ă©s nyomelem felvĂ©telĂ©re
The selenium is an essential trace element with antioxidant effect, constituent of many enzymes, natural component of the body of the animals. The addition to the fish feed as micro element supplementation is generally accepted. Numerous animal experiments veryfied, that the antioxidant effect of the nanoselenium is higher than other selenium forms. But no much information is available of the usuage at fish.
In the experiment were investigated the effects of the nanoselenium supplementation of a commercial fish feed were investigated to the production parameters and the body tissue composition. The correlation between the accumulated selenium content of the body and the treatment, and the feed conversation was also statistically analyzed beside the production parameters. Furthermore we were curious, if can be toxic the nanoselenium in higher doses.
The experimental stock was placed into 12 plastic tanks (each 70 l water vol.) in a recirculation system for larval rearing. The salinity and the water temperature was constant during the 8 week long experiment. The feeding was ad libitum, 4 times a day. Beside the control five (1, 1.5, 2.5, 5.5, 10.5 mg Se kg-1) duplicated treatment were set.
According to the results, from the production parameters only at the value of FCR and the survival was found significant difference (p<0.05) between the groups. However strong correlation (r=0.752–0.780, p<0.01) was determined between the treatment and the accumulated selenium levels. To analyzed the free fatty acid contentof the fish, we realized, that the selenium uptake significanly enhanced this level at all treatments. The greatest change was found in case of the type n-3 fatty acids.
Established by the results, the higher intake than 0.5 mg Se kg-1 was not changed significantly the production parameters, nevertheless to increase the selenium content of commercial feeds to 1.5 mg Se kg-1 could be rewarding on the rearing of red drum
Kutatások a MALDI-TOF tömegspektrometria szĂ©nhidrátkĂ©mia alkalmazási lehetĹ‘sĂ©geinek kiszĂ©lesĂtĂ©sĂ©re = Investigation of widening of the MALDI-TOF MS applications in carbohydrate chemistry
A kutatás fĹ‘ cĂ©lkitűzĂ©se volt szĂ©nhidrátok Ă©s származĂ©kaik (vĂ©dĹ‘csoportokat tartalmazĂł vagy fehĂ©rjĂ©hez kötött oligoszacharidok) MALDI-TOF tömegspektrometriás meghatározásához optimális kĂsĂ©rleti körĂĽlmĂ©nyek megállapĂtása Ă©s Ăgy a szĂ©nhidrátkĂ©miai kutatások segĂtĂ©se. Ciklodextrin modellvegyĂĽletek alkalmazásával vizsgáltuk a minta elĹ‘kĂ©szĂtĂ©s Ă©s felvitel valamint a kĂsĂ©rleti paramĂ©terek változtatásának hatását a spektrumra. Tanulmányozzuk a mátrix anyagának, a minta koncentráciĂłjának, a mintafelvitel mĂłdjának Ă©s a reflektron detektor Ă©rzĂ©kenysĂ©g hatását a spektrum minĹ‘sĂ©gĂ©re. VĂ©dĹ‘csoportokat tartalmazĂł oligoszacharidok mĂ©rĂ©sekor számos törvĂ©nyszerűsĂ©get figyeltĂĽnk meg a vĂ©dĹ‘csoportok stabilitása, a kĂĽlönbözĹ‘ mátrixok Ă©s kĂsĂ©rleti paramĂ©terek között. A MALDI mĂ©rĂ©sek segĂtettĂ©k a termĂ©kek Ă©s mellĂ©ktermĂ©kek azonosĂtását kĂ©miai Ă©s enzimes oligoszacharid szintĂ©zisek esetĂ©ben. FragmentáciĂłs vizsgálatokkal kĂ©miai Ă©s enzimatikus szintĂ©zissel előállĂtott oligoszacharidok, valamint termĂ©szetes eredetű amiláz inhibĂtorok szerkezet felderĂtĂ©sĂ©t vĂ©geztĂĽk el. Meghatároztuk kĂĽlönbözĹ‘ neoglikoproteinek oligoszacharid tartalmát, amely meghatározĂł a sikeres immunválasz kiváltásában. MĂ©rĂ©seinkkel támogattuk a kĂĽlönbözĹ‘ neoglikoprotein előállĂtási mĂłdszerek szisztematikus vizsgálatát. | The object of this research program was the application of MALDI-TOF MS in the field of carbohydrates and glycoconjugates. Cyclodextrins as model compounds were used to investigate the effect of the sample preparation methods and experimental parameters on the spectrum. The studied experimental parameters were: different matrix compounds, detector sensitivity, sample concentration and sample preparation methods. The stability of the protecting groups under the conditions of the evaporation/ionization was studied. The MALDI measurements assisted to identify products and byproducts of different chemical and enzymatic oligosaccharide syntheses (eg. sugar-sulfonates, sulfonic acid esters, PNP-glycosides and acarbose derivatives). Structural analysis and verification were made using post source decay fragmentation method in case of a tetrasaccharid component of N-glycanes, acarbose and its derivatives obtained by enzymatic synthesis and some natural alpha-amylase inhibitors. In addition we used this method for determination of molecular masses of neoglycoproteins
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