THERMAL-ANALYSIS OF BACTERIOPHAGE-T4

The process of bacteriophage T4 morphogenesis was studied using a heat leakage scanning calorimeter. Thermograms of defective mutant 49 (am NG727) in permissive and non-permissive cells of Escherichia coli showed a difference in thermal properties between packaged and non-packaged DNA molecules. In vivo, non-packaged DNA carried out their thermal transition at 85°C, the same temperature as that of T4 DNA melting measured in the standard saline citrate buffer, while the packaged DNA gave a sharper peak at 87°C due to some interaction with the head shell structure. Empty head shells showed a sharp heat absorption peak at 89°C both in vivo and in vitro, indicating the high degree of cooperativity in their conformational changes. © 1979.