Profiling the Glycoforms of the Intact α Subunit of Recombinant Human Chorionic Gonadotropin by High-Resolution Capillary Electrophoresis-Mass Spectrometry

With the rapid growth of complex heterogeneous biological molecules, effective techniques that are capable of rapid characterization of biologics are essential to ensure the desired product characteristics. To address this need, we have developed a method for analysis of intact glycoproteins based on high-resolution capillary electrophoretic separation coupled to an LTQ-FT mass spectrometer. We evaluated the performance of this method on the α subunit of mouse cell line-derived recombinant human chorionic gonadotrophin (r-αhCG), a protein that is glycosylated at two sites and is part of the clinically relevant gonadotrophin family. Analysis of r-αhCG, using capillary electrophoresis (CE) with a separation time under 20 min, resulted in the identification of over 60 different glycoforms with up to nine sialic acids. High-resolution CE−Fourier transform mass spectrometry (FT-MS) allowed separation and analysis of not only intact glycoforms with different numbers of sialic acids but also intact glycoforms th...