Removal of embryo‐toxic ammonium from the culture medium by in situ enzymatic conversion to glutamate

Abstract

An enzymatic method for removing embryo‐toxic ammonium from culture medium has been developed. Ammonium, produced by both embryo metabolism and spontaneous breakdown of amino acids at 37°C, is transaminated by glutamate dehydrogenase to nontoxic glutamate. Initially, the individual components of the transamination reaction were titrated against mouse embryo development in vitro to determine embryo‐safe levels. ADP, an allosteric activator of glutamate dehydrogenase, was found to inhibit embryo development and was therefore omitted from the final formulation (α‐ketoglutarate, 0.44 mM; glutamate dehydrogenase, 0.375 U; NADH, 0.12 mM). It was found that 0.30 mM ammonium could be removed from th..