Teruyuki Fujita

Differential scanning calorimetry of various mutant DNAs of plasmid

Abstract Differential scanning calorimetry of a linear double-stranded plasmid DNA showed a multimodal profile characteristic of the plasmid. This demonstrates that the helix-coil transition of DNA occurs blockwise along the DNA chain. From the results of the analysis of plasmid derivatives having deletions and duplications, the peaks of the DSC curves are assigned at regional sequences including DNA insertion element IS 1 present in the plasmid. The small change in a plasmid DNA sequence caused by cleavage of a plasmid with different restriction enzyme was also clearly reflected on their DSC curves.

Thermal analysis of bacteriophage T4

Abstract 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.

Design and testing of a calorimeter for biological uses

Abstract A rotatory microcalorimeter of the conduction type has been designed for the study of microbial metabolic processes under both aerobic and anaerobic conditions. The instrument can be performed in either batch mode or flow mode by changing the calorimeter vessels and the tube connections. The sensitivity and the time constant were determined by electrical calibrations. The heat sensitivity was 0.12 mV/mW with both yeast and other fungi. Because of the sufficient aeration and agitation, the calorimeter is available for studies on the fungi growth experiments of biotechnical interest.

Low temperature DSC for biological systems

Abstract Design and testing of a low temperature DSC of conduction type with high sensitivity using larger vessels of about 1.5 ml were described. The main technical characteristics of DSC are as follows: operational temperature range is −150–120°C; rate of cooling and heating is 0.01~1°C/min; volume of calorimetric vessels are 1 ml; sensitivity is 3.68μJ/sec/μV; accuracy of temperature recording is 0.1 °C. Test experiments on starches, proteins and alcoholic drinks indicate that the DSC is available for studies on dilute solutions and solids of biological materials and also on the biological-water systems.