Analyzing glycans cleaved from a biotherapeutic protein using ultrahigh-resolution ion mobility spectrometry together with cryogenic ion spectroscopy

Glycans covalently attached to protein biotherapeutics have a significant impact on their biological activity, clearance, and safety. As a result, glycosylation is categorized as a critical quality attribute that needs an adequate analytical approach to guarantee product quality. However, the isomeric complexity and branched structure of glycans makes their analysis a significant challenge. In this work, we propose a multidimensional approach for monitoring released glycans that combines ultrahigh-resolution ion mobility spectrometry (IMS) and cryogenic vibrational spectroscopy, and we demonstrate this technique by characterizing four N-glycans cleaved from the therapeutic fusion protein etanercept that range in abundance from 1% to 22% of the total N-glycan content. The recorded vibrational spectra exhibit well-resolved transitions that can be used as a fingerprint to identify a particular glycan. This work represents an important advance in the analysis of N-linked glycans cleaved from biopharmaceutical proteins that could eventually be used as tool for monitoring biopharmaceutical glycoforms.