Mass Spectrometry 2021

Sponsored by SCIEX

Etanercept is a recombinant Fc fusion protein therapeutic, targeting inflammation regulation. It binds to the receptors TNFR and p75 to block adverse inflammation at the cellular level and has a complex distribution of post-translation modifications (PTM), such as N and O-linked glycans. Current CID-based MS/MS can struggle to characterize such PTMs, since side-chain species are typically fragmented via a mechanism that does not produce diagnostic ions related to the PTM localization. Other forms of fragmentation, such as ETD, can maintain side chain information but suffer from low sensitivity and scan rate, as well as inadequate coverage of low charge state peptides. In this study, a new form of fragmentation (electron activated dissociation, or EAD) was employed to comprehensively characterize the glycosylation of etanercept at the peptide level. A comparative analysis between intact/subunit and peptide mapping results was performed as a validation step for the novel EAD workflow. A total of 149Three N linked glycosylations were detected, as well as nine sites of O-linked glycosylation, with high confidences, via a single, generic, data-dependent LC-MS/MS analysis. Even in challenging cases, exact positioning information of the glycosylation on the peptide could be obtained. In addition, EAD allows for confirmation of amino acid isomers (Leu/IsoLeu and Asp/IsoAsp) via MS/MS analysis, in the same experiment, which will be presented as well.

Sponsored by MOBILion Systems

How can High-Resolution Ion Mobility Mass Spectrometry (HRIM-MS) address the challenges of large molecule characterization? This seminar will discuss the benefits of HRIM-MS in enhancing structural characterization of large molecule therapeutics, while increasing throughput and reducing reliance on LC-based methods. Specific focus will be on how HRIM-MS provides more complete information on coeluting structural isomers, as well as and on emerging workflows.

Sponsored by Waters Corporation

Biopharmaceutical processing and manufacturing can produce a variety of post-translational modifications (PTMs) that may affect drug efficacy and safety. High resolution mass spectrometry (HRMS) is commonly used to characterize these modifications. The unique design and capability of the SELECT SERIES CYCLIC IMS mass spectrometer allows for innovative and versatile investigation of complex analytes via ion mobility separations and a variety of data acquisition modes (The CYCLIC IMS increases the resolution in the mobility dimension by giving flexibility to the number of passes that analytes are sent around the drift tube for separation. This capability is critical to resolve isobaric species such as aspartic acid peptide isomers (e.g. beta amyloid 1-16). IMSn can be performed by selecting species separated in the cyclic device to send to pre-store for re-injection for further ion mobility separation.

The separation in the mobility dimension also allows for truncated LC run times without losing sequence coverage for complex samples. This is advantageous for HDX (hydrogen deuterium exchange) analysis, as the shorter run time minimizes back-exchange and (improved instrument performance) increases peptide identifications, thereby providing more confidence in inferences on higher order structure.

In addition to the aforementioned benefits, the CYCLIC IMS gives versatility in fragmentation experiments performed in the trap or transfer cells, pre- or post- mobility separation, respectively. An ECD cell can be installed for orthogonal fragmentation experiments. ECD is especially useful for labile modifications such as phosphorylation and glycosylation, as will be discussed for O-glycopeptides of erythropoietin (EPO). One can also employ fragmentation to glycopeptides to produce oxonium ions, which can then be analyzed by ion mobility to probe their gas phase confirmation and therefore distinguish linkage isomers. The benefits of cyclic IMS, including flexibility in experiment design, improved sensitivity, and mass resolution provides the tools needed to answer complex questions in biopharmaceutical characterization.