COMPREHENSIVE MASS SPECTROMETRY STUDIES FOR STRUCTURAL CHARACTERIZATION AND QUANTITATIVE DETERMINATION OF HETEROGENEOUS CARBOHYDRATE MOIETIES DERIVED FROM GLYCOPROTEINS FOR THERAPEUTIC PROTEIN DEVELOPMENT AND BIOMARKER DISCOVERY
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Doctor of Philosophy (PhD)
In this dissertation, two mass spectrometry techniques, covered in Chapter 1, have been employed for qualitatively and quantitatively characterizing protein-derived carbohydrate moieties, including N- and O-glycopeptides as well as free glycans derived from biological specimens. In Chapter 2, an RP-LC-MS/MS system functionalized with multiple fragmentation performances, specifically CID and HCD, is utilized to survey all probable N- and O-glycosites along the backbone of a coagulation factor, human plasma von Willebrand Factor, with full characterization of covalently linked N- and O-glycoforms. N-glycosite occupancy varied along the protein backbone chain. 181-characterized glycoforms are specified into either N- or O-glycosites. Noteworthy, two previously unreported N-glycosites within domain D’(TIL’-E’) are occupied with N-glycoforms. In Chapter 3, MALDI-TOF technique is utilized to explore aberrant N-glycosylation in the frontal cortex (FC) region extracted from Alzheimer Disease (AD) patients’ brains in comparison with age-matched individuals. AD FC N-glycome exhibits a significant decrease in galactosylation and fucosylation as well as sialylation compared to normal FC. Eight N-glycoforms, detected across all cases, are significantly differentiated between the examined cohorts. Also, high mannose, hybrid, complex, and truncated N-glycans are considerably changed in disease tissues. In Chapter 4, altered N-glycosylation of soluble serum glycoproteins derived from colon cancer (CC) patients’ blood sera is characterized by MALDI-TOF. N-glycome of CC glycoproteins shows an increase in aglactosylation, fucosylation, and sialylation, especially sialylated core-fucosylated species. The knowledge of this work (Chapter 5) might improve our perception of disease pathogenesis or enhance the efficacy of current therapy treatments.
Gashash, Ebtesam, "COMPREHENSIVE MASS SPECTROMETRY STUDIES FOR STRUCTURAL CHARACTERIZATION AND QUANTITATIVE DETERMINATION OF HETEROGENEOUS CARBOHYDRATE MOIETIES DERIVED FROM GLYCOPROTEINS FOR THERAPEUTIC PROTEIN DEVELOPMENT AND BIOMARKER DISCOVERY." Dissertation, Georgia State University, 2019.
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