GLUTAMINE-BASED DIPEPTIDES ARE UTILIZED IN MAMMALIAN-CELL CULTURE BY EXTRACELLULAR HYDROLYSIS CATALYZED BY A SPECIFIC PEPTIDASE

A murine hybridoma (CC9C10) was grown in media containing alanyl-gluta mine (ala-gln) or glycyl-glutamine (gly-gln) as a substitute for gluta mine. High cell yields were obtained in the presence of 6 mM ala-gln o r 20 mM gly-gln. The final cell yield in gly-gln was 14% higher than i n gin. Monoclonal antibody productivity was comparable in gin, ala-gln or gly-gln. Substrate utilisation and metabolism was affected by the presence of the dipeptides, particularly with gly-gln. The specific co nsumption rates of glucose and six amino acids were reduced. Also the accumulation of ammonia and lactate was significantly lower. The highe r concentration of gly-gln was necessary for cell growth because of th e presence of a peptidase with a lower affinity for gly-gln. The pepti dase activity of the basal medium and serum was low. However, a substa ntial peptidase activity was found in the cytosolic fraction of the ce lls with an apparent K-m of 1.2 mM with respect to ala-gln and 14 mM w ith respect to gly-gln. It is proposed that the mechanism of dipeptide utilisation involves extracellular hydrolysis by this peptidase follo wing its release into the culture medium.