[Application of tiazofurin in the study of regulation of AMP deaminase in intact malignant cells].

AMP deaminase has a key position in regulation of the pool of adenine nucleotides and energetics in malignant cells. The aim of this investigation was to elucidate mechanism of regulation of activity of AMP deaminase in intact tumor cells. Using tiazofurin, which profoundly decreases the level of GTP, and guanosine which markedly increases its concentration in the Ehrlich ascites tumor cells under aerobic conditions, we have shown that this nucleotide is probably the major regulator of AMP deaminase activity in situ. This regulation, however, should be considered in relation to the time and the changes which occur during transition of the cells from aerobic to anaerobic phase, and reverse, when other factors, like concentrations of the substrate and ATP are involved.