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Metabolite Activation and Glycine Accumulation in Ehrlich Ascites Tumor¹

Institut für Vegetative Physiologie der Universität Frankfurt/Main, Germany

The addition of several metabolites to the incubation mixture increases the rate of glycine accumulation by the American strain of tetraploid Ehrlich ascites tumor cells. For determination of the mechanism of this stimulatory effect, the energetic status of cells was estimated by their ATP content and the extent of glycine incorporation into protein, which were concurrently measured.

It was observed that glucose, fructose, pyruvate, lactate, and oxalacetate stimulated glycine accumulation to the same extent, more than 50%, after 90 min. These metabolites simultaneously increased the cellular ATP level. Succinate, -ketoglutarate, acetate, and linoleate had less effect on glycine accumulation. However, linoleate could not be tested by the use of concentrations comparable to those of other metabolites, since the latter have inhibitory effects. Alanine, valine, asparagine, and glutamine were also tested for their action on glycine accumulation, which was increased only by glutamine. After 90 min, approximately 20% stimulation by glutamine occurred without a simultaneous increase in cellular ATP level. The rate of glycine incorporation into protein was double that of control levels when glucose, fructose, pyruvate, oxalacetate, and alanine were added over a 2-hr period. Lactate and glutamine had even greater effects. The stimulated accumulation could be partially blocked by actidione (cycloheximide) or puromycin, suggesting that this effect of metabolites is, in part, the result of stimulated protein synthesis. Supporting this hypothesis is the finding that nonmetabolized galactose also stimulated the three parameters that were measured, namely, glycine accumulation, glycine incorporation into protein, and cellular ATP level.

¹ This work was supported by Deutsche Forschungsgemeinschaft. Part of this work was presented at the Sixth Meeting of the Federation of European Biochemical Societies Meeting in Madrid, Spain, in 1969.

² Present address: Georg Speyer-Institut, Paul Ehrlich-Strasse 44, Frankfurt/Main, Germany.

Received 8/23/71. Accepted 6/ 1/72.