Effect of glucose and various nucleosides on purine synthesis by Ehrlich ascites tumor cells in vitro.

The pattern of formate-Cl4 incorporation by Ehrlich ascites tumor cells has been found to be remarkably different in vitro from the pattern of incorporation in vivo (3-5). Thus, after incubation of cells with formate-Cl4 in vitro, the specific activity of the DNA thymine was 10 to 30 times higher than that of the DNA purines. In contrast, after incorporation of formateCl4 by these cells in viva, the specific activity of DNA thymine was similar to that of the DNA purines. The deficiency in purine synthesis de nova in the system in vitro could be partially alleviated by the addition of AICY (3) or pigeon liver extract (4). However, addition of these substances did not influence the incorporation of P32 into nucleic acids or of formate-Cl4 into DNA thymine (3). The present report is concerned primarily with the effect of glucose and various other compounds on formateCl* incorporation into purines in the system in vitro.