The Impact of Glycation on Protein Color

Health Authorities expect that color of liquid formulations of monoclonal antibodies be monitored and controlled.  Subcutaneous drug formulations often require high drug substance concentrations which may result in more intense product color. A potential mechanism of coloration is through the Maillard reaction, where reducing sugars in the cell culture media react with the secreted protein product in a series of non-enzymatic reactions that result in formation of glycated protein and advanced glycation end products (AGEs). We varied the glucose feeding strategy and cell culture media across multiple cell lines to study and delineate the effects. Presence of AGEs was also measured using mass spectrometry. We observed good correlation between the glucose fed to the culture and the level of the glycated protein.  However, the glucose feeding strategy tested did not significantly impact color, and we observed no strong correlation between glycated protein and color.  Changes in the levels of the AGEs for different culture conditions will also be discussed.