EFFECT OF FERRITIN ON LAMBDA-DNA STRAND BREAKS IN THE REACTION SYSTEMOF ALLOXAN PLUS NADPH-CYTOCHROME P450 REDUCTASE - FERRITINS ROLE IN DIABETOGENIC ACTION OF ALLOXAN

The incubation of lambda DNA in the reaction system of alloxan plus NA DPH-cytochrome P450 reductase (fp2) in the presence of ferritin caused strand breaks after a lag time of about 5 min. Addition of ferritin t o the reaction system at concentrations below 50 mu g/ml caused the st rand breaks of DNA in a concentration-dependent fashion. Catalase, sca vengers of hydroxyl radicals (HO .) and iron-chelators almost complete ly inhibited the DNA strand breaks, but superoxide dismutase (SOD) did not, suggesting that the strand breaks are induced by the generation of HO . via the reaction of H2O2 and Fe(II), namely, the Fenton reacti on. When the ferritin was incubated in the reaction system of alloxan plus fp(2), the iron release from ferritin increased with incubation t ime depending on the amount of fp2. The addition of increasing concent rations of ferritin to the reaction system resulted in progressive inc rease in the iron release and a decrease in the electron spin resonanc e signal intensity of alloxan radical (HA .), the one electron reduced form of alloxan, suggesting that HA . generated in the reaction syste m is capable of releasing iron from ferritin. These results support th e possibility that the iron released from ferritin may be involved in the diabetogenic action of alloxan.