Magnetic Isotope Effect on the Repair of Radiation-Induced DNA Damage

摘要

The rate of DNA repair in human blood lymphocytes exposed to gamma-radiation was shown to depend on the nuclear magnetic moment of magnesium ions. The decrease of DNA double-strand breaks occurs as a first-order reaction with the rate constants 1.1 x 10(-3) s(-1) and 1.6 x 10(-3) s(-1) for Mg-25(2+) and Mg-24(2+) ions respectively. Their ratio certifies magnetic isotope effect on the DNA repair; the latter occurs by 1.5 times slower with nuclear-magnetic Mg-25(2+) ions than with nuclear nonmagnetic Mg-24(2+) ions. The discovery of this effect is an irrefutable indicator that the DNA repair is spin-dependent and magneto-sensitive process, and its chemistry includes electron transfer and generation of radicals and radical pairs.