The Incorporation in Vitro of C’” into Amino Acids of Control and Virus-infected

Previous studies (1, 2) have shown that radioactive carbon from uniformly labeled glucose is incorporated in vitro into all of the protein-bound amino acids except proline and threonine by minced 1 day-old mouse brain. Inoculation of such preparations with Theiler’s GD VII mouse encephalomyelitis virus resulted in extensive virus propagation and an increased incorporation of radioactivity into all of the labeled amino acids except lysine and histidine. The distribution of radioactivity in the various amino acids was extensive and made difficult the interpretation of the intermediary pathways by which this incorporation may have occurred and the nature of the reactions affected by virus infection. It seemed possible that a study of the incorporation of simpler substrates into the protein-bound amino acids might be more simply interpreted. In the present study, therefore, the extent of incorporation of radioactive carbon from C4-labeled acetate, formate, and bicarbonate into the protein-bound amino acids of mouse brain has been investigated.