By Dr. Martin Schilling, Senior Product Manager for Cell Culture Ingredients, Evonik Health Care
L-Cysteine and its oxidized form L-Cystine are essential amino acids used in cell culture and are present in all chemically defined media formulations. Both forms can be taken up by most cell lines, including those used in monoclonal antibody production.
L-Cysteine is not only an important building block of biomass and recombinant proteins, but it also has additional functions. It is the rate limiting substrate in the biosynthesis of glutathione, which is the main mediator of intracellular redox homeostasis and helps to reduce oxidative stress. Thus, providing sufficient Cys-equivalents is critical to achieve the best bioprocess performance, when cultivating cells in serum-free, chemically defined conditions.