A MALDI-TOF MS method for the simultaneous and quantitative analysis of neutral and sialylated glycans of CHO-expressed glycoproteins

The development of a MALDI-TOF MS method for the quantitative analysis of the glycosylation of CHO-expressed biotherapeutic glycoproteins shall be presented. The method utilizes a well-established chemistry, reductive amination of glycans, to derivatize glycans with either a light analog ((12)C(7) anthranilic acid) or a heavy analog ((13)C(7) anthranilic acid) to allow for the direct comparison of the alternately-labeled glycans by MALDI-TOF MS. The method allows for the simultaneous analysis of neutral and sialylated glycans and displays a linear dynamic range over two orders of magnitude with sub-picomolar sensitivity. Additionally, because the glycans are derivatized with anthranilic acid, which is a very sensitive fluorophore, the glycans can be analyzed by chromatography with fluorescence detection. The need for this type of method is highlighted by the biotechnology/biopharmaceutical industry's continuous drive towards fully understanding process control. By providing this type of quantitative data, glycosylation changes of the expressed protein can be easily observed thereby helping to further advance the understanding of a major aspect of the biopharmaceutical process.