Abstract
Glutamine was produced by coupling the glutamine synthetase from Micrococcus glutamicus with sugar fermentation of baker's yeast as an energy-generating system. With 429 units/ml of glutamine synthetase and 40mg/ml of yeast cells, 120mM of glutamate was converted completely to glutamine in 3-4hr, and 160-170mM of glutamine (approximately 23-25g/l) was formed in 5hr from 350mM of the substrates glutamate and ammonium chloride with a yield of about 40%, based on the energy released by the yeast during sugar fermentation. The activity ratio of sugar fermentation and glutamine synthetase was again confirmed to be important for achievement of energy-coupling in systems with high concentrations of glutamate and ammonium chloride. Glutamine formation was partially stimulated by the addition of Mg2+ in concentrations at which yeast fermentation of sugar showed no response to the cation, but was greatly stimulated by the addition of a small amount of Co2+. This same Co2+ effect was also observed in the reaction with cell-free extracts or toluol-treated cells of M. glutamicus.
