Apparent synergism between amino donors for CTP synthesis in Chinese hamster fibroblasts

Abstract

The synergistic effects of potential amino donors were studied in the assay of CTP synthetase in extracts of Chinese hamster fibroblasts. We found that L-glutamine was not effective as the sole amino donor, but combinations of L-glutamine with NH 4 HCO 3 , L-arginine or potassium phosphate did result in the conversion of UTP to CTP. L-arginine or potassium phosphate were also not effective when used alone, and NH 4 HCO 3 was only slightly effective. Our studies demonstrate that the individual synergistic combinations were not additive; multiple combinations of components decreased rather than increased the formation of CTP.