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Chemical modifications of hydrogels from natural polysaccharide
Poštulková, Hana ; Žídek, Jan (oponent) ; Vojtová, Lucy (vedoucí práce)
Chemical structure, use and chemical and physical properties of natural polysaccharide gum karaya (Sterculia urens) were summarized in theoretical part of this work. The general goal of the diploma work was modification of original insoluble gum karaya under alkali condition to prepare water soluble sample for further applications. Insolubility of gum karaya is caused by presence of acetyl groups and multivalent ions in the structure of polysaccharide. Optimized conditions for modification process were investigated. Sodium, potassium or ammonium hydroxide, 1 minute to 24 hours of treatment and 0.1 - 3% solution of original gum karaya were used for optimizing the modification process. Original (OGK) and modified (MGK) samples were studied by FTIR to investigate chemical composition. Modified samples A2, B1-7, C1-8 and E1-2 were considered as fully deacetylated because of absence of band at 1725 cm-1 which represents acetyl group. Absence of acetyl groups after modification was also proved by 13C CP MAS NMR. Amorphous character of original gum karaya was determined by XRD. TGA was used to evaluate amount of moisture and thermal stability of original and modified samples. Thermal stability of OGK was higher (280 °C) than of modified samples. Thermal stability of MGK was affected by reaction parameters. Thermal changes in polysaccharide chains were studied by DSC but any significant differences between OGK and MGK were not observed. Mineral composition of original and modified samples was investigated by ICP OES and presence of calcium, potassium and magnesium ions in OGK was confirmed. Molecular weight of modified samples was evaluated by GPC and was approximately 8 million g·mol-1. Rheological measurement for determination of linear viscoelastic region was determined. Effect of NaCl on viscosity of original gum karaya was performed. Viscosity of OGK decreased with higher amount of NaCl. Lower viscosity of OGK is connected with exchange of Ca2+ for Na+ ions and release of the physically bonded structure resulting in higher solubility of OGK in water.
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Role histon deacetylázy 6 v replikačním cyklu myšího polyomaviru
Vlachová, Štěpánka ; Horníková, Lenka (vedoucí práce) ; Saláková, Martina (oponent)
Replikační cyklus polyomavirů je stejně jako u ostatních virů zcela závislý na hostitelských buňkách. Pro viry je důležitý nejen buněčný replikační a translační aparát, ale virovou infekci ovlivňují také další buněčné proteiny. Tato práce se zabývá rolí hlavní cytoplazmatické deacetylázy histon deacetylázy 6 (HDAC6) v replikačním cyklu myšího polyomaviru (MPyV). Podařilo se nám prokázat, že přítomnost plně funkční HDAC6 je nezbytná pro úspěšnou a produktivní infekci. Zjistili jsme, že HDAC6 ovlivňuje jak časné, tak i pozdní fáze infekce. Při inhibici, či úplně absenci tohoto proteinu v buňkách je MPyV infikuje s menší efektivitou a zároveň při infekci vzniká méně infekčního virového potomstva. Naopak při využití buněk s částečně funkční HDAC6 schopnou buď deacetylace či vazby ubiquitinu se schopnost MPyV infikovat tyto buňky zvyšuje. Analýzou hladin časného LT antigenu a pozdního strukturního proteinu VP1 jsme prokázali, že HDAC6 ovlivňuje jejich hladiny v infikovaných buňkách. Naše data také naznačují, že v replikačním cyklu MPyV je vyžadována přítomnost především ubiquitin-vazebné domény HDAC6 a s ní spojená funkce v metabolismu a degradaci virových a buněčných proteinů. V druhé části diplomového projektu jsme se zaměřili na přípravu expresních plazmidů nesoucích časnou genovou oblast kódující...
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Chemical modifications of hydrogels from natural polysaccharide
Poštulková, Hana ; Žídek, Jan (oponent) ; Vojtová, Lucy (vedoucí práce)
Chemical structure, use and chemical and physical properties of natural polysaccharide gum karaya (Sterculia urens) were summarized in theoretical part of this work. The general goal of the diploma work was modification of original insoluble gum karaya under alkali condition to prepare water soluble sample for further applications. Insolubility of gum karaya is caused by presence of acetyl groups and multivalent ions in the structure of polysaccharide. Optimized conditions for modification process were investigated. Sodium, potassium or ammonium hydroxide, 1 minute to 24 hours of treatment and 0.1 - 3% solution of original gum karaya were used for optimizing the modification process. Original (OGK) and modified (MGK) samples were studied by FTIR to investigate chemical composition. Modified samples A2, B1-7, C1-8 and E1-2 were considered as fully deacetylated because of absence of band at 1725 cm-1 which represents acetyl group. Absence of acetyl groups after modification was also proved by 13C CP MAS NMR. Amorphous character of original gum karaya was determined by XRD. TGA was used to evaluate amount of moisture and thermal stability of original and modified samples. Thermal stability of OGK was higher (280 °C) than of modified samples. Thermal stability of MGK was affected by reaction parameters. Thermal changes in polysaccharide chains were studied by DSC but any significant differences between OGK and MGK were not observed. Mineral composition of original and modified samples was investigated by ICP OES and presence of calcium, potassium and magnesium ions in OGK was confirmed. Molecular weight of modified samples was evaluated by GPC and was approximately 8 million g·mol-1. Rheological measurement for determination of linear viscoelastic region was determined. Effect of NaCl on viscosity of original gum karaya was performed. Viscosity of OGK decreased with higher amount of NaCl. Lower viscosity of OGK is connected with exchange of Ca2+ for Na+ ions and release of the physically bonded structure resulting in higher solubility of OGK in water.
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