Improvement and simplification of fed-batch bioprocesses with a highly soluble phosphotyrosine sodium salt

Fed-batch culture bioprocesses are currently used predominantly for the production of recombinant proteins, especially monoclonal antibodies. In these cultures, concentrated feeds are added during cultivation to prevent nutrient depletion, thus extending the cellular growth phase and increasing product concentrations. One limitation in these bioprocesses arises from the low solubility or stability of some compounds at high concentrations, in particular amino acids. This study describes the synthesis and evaluation of a phosphotyrosine disodium salt as a tyrosine source in fed-batch processes. This molecule is highly soluble in concentrated feeds at neutral pH. Mechanistic studies demonstrated that the molecule is cleaved in the cell culture supernatant after processing by released phosphatases, leading to phosphate and free L-tyrosine which can be taken up by the cells. No intact phosphotyrosine was detected intracellularly or incorporated into the sequence of the monoclonal antibody. The use of this new molecule allows the simplification of fed-batch processes in large scale manufacturing via the implementation of neutral pH, highly concentrated feeds.