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    Characterization of Monoclonal Antibody N-Glycan Conformations by Novel Hydrophilic Interaction Liquid Chromatography (HILIC) with Trapped Ion Mobility Mass Spectrometry (TIMS) and Fluorescence Detection (FLD)
    (Taylor & Francis Inc, 2024) Avci, Izzet; Atakay, Mehmet; Kayili, Haci Mehmet; Salih, Bekir
    Monoclonal antibodies (mAbs) have become prevalent in the pharmaceutical sector for treating various diseases and have a significant market presence. The determination of these molecules is complex and challenging. It is necessary to employ high-throughput technologies to characterize these pharmaceuticals in order to characterize sequencing, structure, composition, conformation, and mass. It is important to perform an N-glycosylation study on these macromolecules as their N-glycan profiles have a significant impact on their effectiveness. However, the conformational features of the N-glycans on mAb are not adequately addressed in commonly used methods. This study incorporated ion-mobility mass spectrometry as an additional dimension to established hydrophilic liquid chromatography trapped ion mobility spectrometry with fluorescence detection ((HILIC)LC/TIMS/FLD) in order to enhance the characterization of N-glycan structures. The N-glycans derived from two distinct mAbs and an immunoglobulin G (IgG) protein were labeled with procainamide and determined by (HILIC)LC/FLD with TIMS. The N-glycan profiles obtained from mAbs and IgG were examined in terms of conformation. The alterations in the N-glycan conformations were ascertained with the insertion of distinct monosaccharide units, such as galactose, into the structure. This method can be employed to clarify the intricate structures of N-glycans and offer insights into the conformational features of monoclonal antibodies throughout their production.
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    Characterization of serum N-glycome alterations in seasonal allergic rhinitis using MALDI-TOF-MS: A pilot study
    (Taylor & Francis Inc, 2021) Yaman, Mehmet Emrah; Avci, Izzet; Atila, Nihal Efe; Atila, Alptug; Kayili, Haci Mehmet; Salih, Bekir
    Seasonal allergic rhinitis (SAR) is an inflammatory process. In this pilot study, matrix assisted laser desorption ionization-mass spectrometry (MALDI-MS)-based analyses were conducted to investigate the effects of SAR on serum N-glycome in a small dataset (n = 10 for both SAR patients and controls). It was detected that two N-glycan compositions (H6N5E2L1 and H6N5E1L2) were down-regulated in SAR patients. Additionally, five tri-antennary N-glycan traits, including both galactosylated and sialylated (A3GS and A3GL) and non-fucosylated (A3F0GE, A3F0GL, A3F0GS) ones, were decreased. Furthermore, three high-antennary and fucosylated N-glycan traits (A3F, A3EF and A4F) were increased in SAR patients compared to controls.
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    A New titania glyco-purification tip for the fast enrichment and efficient analysis of glycopeptides and glycans by MALDI-TOF-MS
    (Elsevier, 2019) Kayili, Haci Mehmet; Avci, Izzet; Salih, Bekir
    Enrichment and/or purification of intact glycopeptides and derivatized glycans are essential for mass spectrometry-based glycoproteomics and glycomics because of analytical challenges observed in the analysis. Here, a titania-based material was synthesized using a facile sol-gel method for the efficient analysis of glycopeptides and glycans. The glycopeptide enrichment efficacy of the titania-based sol-gel material was evaluated by the enrichment of IgG N-glycopeptides from their proteolytic products. The selectivity and sensitivity (0.5 fmol mu L-1) of the titania-based sol-gel material was found to be quite high when compared with commercial TiO2. A pipette-tip application for rapid glycoproteomic and glycomic analysis was developed by packing titania-based material into the pipette tips. The released and derivatized N-glycans of human plasma, IgG and human transferrin were successfully purified by titania glyco-purification tips for the analysis by MALDI-MS. The enrichment performance of the titania glyco-purification tip was tested using human plasma digest as a real-world complex sample and, 112 N-glycopeptides from human plasma glycoproteins were detected by the analysis of enriched samples by nLC-QTOF-MS/MS. Finally, the structural characterization of the material was achieved in detail using various characterization approaches. (C) 2019 Elsevier B.V. All rights reserved.