|
|
Effect of elution solution on the enrichment and purification of glycopeptides using SPE-HILIC
Chobotová, Michaela ; Kozlík, Petr (advisor) ; Křížek, Tomáš (referee)
Changes in protein glycosylation are related to various diseases such as cancer or Alzheimer's disease. Unfortunately, the analysis of glycoproteins remains a difficult task due to the low proportion of glycopeptides compared to peptides obtained after glycoprotein cleavage. As a result, it is almost impossible to analyze glycopeptides without specific enrichment steps. A suitable method for the enrichment of glycopeptides is solid phase extraction (SPE) using the principle of hydrophilic interaction liquid chromatography (HILIC). Since the choice of solvent significantly affects the enrichment of glycopeptides, the aim of this thesis was to compare the effect of different solvents on the efficiency of glycopeptide extraction using SPE-HILIC. The extraction was carried out on a silica column modified with aminopropyl groups. Model analytes were glycopeptides obtained by tryptic digestion of human IgG. During the comparsion of acetonitrile, methanol and isopropanol, acetonitrile was chosen as a suitable elution solvent. During the conditioning and washing step, the content of acetonitrile was changed (65%, 75% and 85%), whereby the elution of glycopeptides is accelerated as the amount of acetonitrile decreases. In the elution step, the effectiveness of different acetonitrile contents (5%, 10% and...
|
|
|
Application of capillary electrophoresis in analysis of saccharide component of glycopeptides
Šimonová, Alice ; Křížek, Tomáš (advisor) ; Kubíčková, Anna (referee)
The aim of this thesis was the development of the method for the determination of eight monosaccharides commonly found in glycoproteins by capillary electrophoresis. Namely, it was determination of glucose, galactose mannose, N-acetylglucosamine, N-acetylgalactosamine, fucose, N-acetylneuraminic acid and xylose. Total length of silica capillary with inner diameter of 10 m was 50.0 cm and effective length was 35.0 cm. Background electrolyte was compound of sodium hydroxide of 50 mmol/l concentration, disodium phosphate of 22.5 mmol/l concentration and cetyltrimethylamoniumbromide of 0.2 mmol/l concentration. Samples were injected hydrodynamically with pressure of 5 kPa for 70 s, driving voltage was -30 kV and the pressure of 270 kPa was applied to the outlet vial during the separation; capacitively coupled contactless conductivity detector was used to detect the analytes. The limits of detection were between 5 and 7 mg/l and the limits of quantification were between 16 and 22 mg/l. Repeatability of peak areas and migration times related to 4-(2-hydroxyethyl)-1-piperazinethanesulfonic acid as an internal standard showed values of relative standard deviation lower than 4 %. Conditions for hydrolysis of oligosaccharides to monosaccharides were determined as 4M hydrochloric acid and 100 řC, hydrolysis...
|
|
|
Development and genetic basis of glycopeptide resistance in coagulase-negative staphylococci
Prášilová, Jana ; Balíková Novotná, Gabriela (advisor) ; Lišková, Petra (referee)
Glycopeptides are the so-called last-resort antibiotics in clinical practice used to treat heavier, predominantly nosocomial infections caused by multi-resistant coagulase-negative staphylococci. The origin and genetic basis of resistance to glycopeptide antibiotics has not yet been elucidated within coagulase-negative staphylococci. Research on Staphylococcus aureus has shown, that intermediate resistance to glycopeptide antibiotics is associated with the presence of one or more mutations, rather than being conditioned by the support of a particular genetic element, such as in enterococci. By using various types of in vitro resistant mutant selection, we were able to obtain isogenic pairs of glycopeptide sensitive and resistant strains of Staphylococcus epidermidis and Staphylococcus haemolyticus. By sequencing the genomes of these pairs, one nucleotide polymorphisms were identified and predominantly found in metabolic and cell wall control systems. Phenotypic analysis did not reveal a direct association of glycopeptide resistance with increased biofilm formation. In clinical practice, the cross-resistance of glycopeptides and other antibiotics is problematic. For the non-glycopeptide antibiotics imipenem and rifampicin, the incidence of cross-resistance with glycopeptide antibiotics in S. aureus...
|
|
|
The effect of vanZTei and vanZg expression on resistance to glycopeptide antibiotics in Staphylococcus aureus
Zieglerová, Leona ; Balíková Novotná, Gabriela (advisor) ; Lichá, Irena (referee)
A membrane protein VanZTei which is encoded by the gene vanZ from the vanA glycopeptide resistance gene cluster is a part of the large family of VanZ proteins. VanZTei confers resistance to teicoplanin in Enterococcus faecalis without the presence of other proteins encoded by the cluster. The aim of my work was to compare the ability of two orthologous proteins VanZTei and VanZg (from the genome of Enterococcus faecium) to confer resistance to glycopeptides in Staphylococcus aureus RN4220 and Enterococcus faecium. We have shown that VanZg increases resistance to teicoplanin (Tei) 8 to 16 times the and also to dalbavancin (Dalb) 8 times. VanZTei also confers resistance to Tei and Dalb, but the increase is only twofold. Conversely VanZTei confers resistance to newly synthetized glycopeptides more effectively than VanZg (fourfold increase of resistance confered by VanZTei and two to fourfold increase of resistance confered by VanZg). It suggests that both proteins have different specificity to antibiotics. In despite the mutants of S. aureus RN4220 VanZTei pRMC2 with increased resistance to teicoplanin (MICTei> 8 µg/ml) in which the resistance is dependent on vanZTei expression were selected. These resistant mutants do not carry mutation in a gene vanZTei or in its ribosomal binding site. Neither of the...
|
|
| |
guest ::
