Replacement of Isoleucine and Leucine by their Keto Acids leads to increased formation of α-Hydroxy Acids in Chinese Hamster Ovary cells.

Keto isoleucine and keto leucine are bioavailable amino acid precursors in CHO cells producing biotherapeutics. Following their supplementation in a fed-batch culture with CHOK1 GS cells, quantitation of metabolites derived from the three branched-chain keto acids revealed a decrease of their decarboxylation products, but an accumulation of their α-hydroxy acids. The latter had minor effects on cell growth and productivity. L-lactate dehydrogenase was identified as the key enzyme forming valine's α-hydroxy acid.