Energetics of DNA repair: effects of temperature on DNA repair in UV-irradiated peripheral blood leucocytes from chronic myeloid leukemic patients

The effects of different temperatures (34-430C) were studied on the repair of UV-induced (254-nm) DNA damage and its energetics in peripheral blood leucocytes of chronic myeloid leukaemic patients. DNA repair was measured by the unscheduled DNA synthesis (UDS) technique. Cellular energy supply was modulated by inhibitors of oxidative phosphorylation (antimycin-A) and glycolysis (2-deoxy-D-glucose). It was observed that there is an increase in the amount of DNA repair with increasing temperatures up to 400C and a fall thereafter. Longer periods of heat treatment (4 h) beyond 400C were observed to further decrease the DNA repair. Increasing temperatures were observed to have no significant effect on the parameters of energy metabolism. Further, the activation energy of DNA repair was calculated as 92 ± 46 kJ/mol (22 ± 11 kcal/mol), which did not alter significantly even in the presence of inhibitors of energy metabolism. (author)