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  • Vpliv različnih parametrov na porazdelitveni koeficient licozima v dvokomponentnih vodnih sistemih-polietilen glikol/hidroksietil škrob = Effect of different parameters on partitioning of lysozyme in poly(ethylene glycol)hydroxyethyl starch aqueous biphasic systems : diplomska naloga
    Berglez, Sandra
    There are many factors that influence the partition coefficient K, the ratio of biomolecule concentration in top phase to that in the bottom phase, in aqueous two-phase systems. In this thesis, the ... partition behavior of lysozyme in aqueous two-phase systems was investigated in order to see the effects of changes in phase properties on the partition coefficient K. A system composed of polyethylene glycol (24% (wžw), mol. weight 120000) and hydroxyethyl starch(40% (wžw), mol. weight 200000) was used. Later on, microspheres were built up, and the key step for their preparation was this aqueous two-phase system. In order to achieve greater efficiency of microspheres, enrichment of protein in hydroxyethyl starch phase had to be altered. The pH and choice of salt were found to be the most important factors which influence K. Systems with different concentrations of sodium chloride, potassium chloride, potassium phosphate, sodium phosphate and sodium sulphate were built up. In order to achieve different pH values, acetate, phosphate, and bicarbonate buffer were used. Optimal conditions of these factors were obtained when 100mMsodium sulfate with bicarbonate buffer at pH 8,5 was used with the partition coefficient in this case being 0,16. Bigger selectivity of protein between the phases was assumed to be due to reduced solubility, especially in the polyethylene glycol phase. The pH of the system showed to have effect on lysozyme partition coefficient, higher pH did decrease partition coefficient. Conductivity measurements were made in systems containing different salts in the 20mM - 100mM concentration range. These results showed how ions were distributed. Since anions have much greater tendency to be distributed unevenly between the phases, it can be assumed that difference in distributionis mainly due to anion distribution. This causes difference in electrical potential between the phases. Since lysozyme (isoeletric point 10,0-11,0) is positively charged it is attracted to the negatively charged phase. Chloride was found to accumulate more in polyethylene glycol. In the systems with sodium chloride and potassium chloride higher partition coefficient of lysozyme was obtained. Opposite effect was detected when sulphate or phosphate was used, when the partition coefficient did decrease.
    Vrsta gradiva - diplomsko delo ; neleposlovje za odrasle
    Založništvo in izdelava - Ljubljana : [Berglez, S.], 2006
    Jezik - angleški, slovenski
    COBISS.SI-ID - 1897073

Knjižnica/institucija Kraj Akronim Za izposojo Druga zaloga
Fakulteta za farmacijo, Ljubljana Ljubljana FFALJ v čitalnico 1 izv.
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