GSK-aBAM (aBAM) is a monoclonal antibody designed to bind the soluble target of various beta amyloid peptides (BAM). The aggregation and deposit of BAM in the brain are implicated in the pathogenesis of Alzheimer’s Disease. During the forced degradation study in aBAM development, hydrogen peroxide treated aBAM molecule revealed that methionine oxidation caused a slow increase in aggregation and a highly unusual change in the antigen binding activities. The objectives of this research were to study the binding difference between native and oxidized aBAM using Hydrogen-Deuterium Exchange Mass Spectrometry (HDX MS) and structural modeling, to understand the oxidation induced aggregation by purifying oxidized aBAM monomer and aggregates followed by characterization of each species, and to investigate the aBAM aggregation impact on overall antigen binding activities by Surface Plasma Resonance (SPR). The experimental results determined how the Met34 oxidation and resulting local conformational changes affected the antigen docking grove and increased overall binding in aBAM. Met34 was also elucidated to be the critical residue to aggregation in oxidized aBAM. SPR assay results demonstrated that oxidized monomer has greater than 160% of binding while oxidized aggregates have much lower values. The limitations of HDX MS were also discussed and structural modeling was identified a complementary tool to explain the molecular behavior. The results and knowledge gained in this research can not only lead to a proper controlling strategy for GSK-aBAM, but also be used to help the design of future medicines.
|School:||University of the Sciences in Philadelphia|
|School Location:||United States -- Pennsylvania|
|Source:||DAI-B 77/04(E), Dissertation Abstracts International|
|Keywords:||Aggregation, Antigen binding, Beta amyloid peptide, Hydrogen deuterium exchange mass spectrometry, Monoclonal antibody, Oxidation|
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