Stable magnetic isotopes: from spin chemistry to biomedicine

Abstract

Biomolecular nanoreactors, like other cell structures, are composed of atoms of chemical elements many of which have magnetic and non-magnetic stable isotopes. The so-called magnetic isotope effect well known in spin chemistry is a direct consequence of the law of conservation of the electron angular moment (spin) and manifests itself in the fact that chemical reactions with participation of free radical pairs or ion-radical pairs exhibit different reaction rates and different yields of products according to whether the reactants contain magnetic or nonmagnetic isotopes. The magnetic isotope effects in the enzymatic catalysis were first discovered in the pioneering works of Russian scientists, A. L. Buchachenko and his co-workers. Our team studied living cells enriched in different isotopes of magnesium and discovered for the first time the magnetic isotope effects (nuclear spin catalysis) in vivo. The magnetic isotope 25Mg was much more efficient than the non-magnetic isotope 24Mg in stimulating the recovery processes of the S. cerevisiae yeast cells after short-wavelength UV irradiation. The E. coli bacterial cells are adapted substantially faster to a new growth medium containing magnetic 25Mg than to a medium containing non-magnetic 24Mg or 26Mg. Furthermore, the effects of magnesium isotopes on the muscle protein myosin were investigated in cooperation with Ukrainian biochemists and stimulation of the ATPase activity of the enzyme by the magnetic 25Mg isotope 2–2.5 times exceeding the enzyme activity in the presence of non-magnetic magnesium isotopes was detected. Detailed physicochemical mechanisms of the magnetic isotope effects in the enzymatic catalysis and elucidation of the biological mechanisms of enhancement of these effects in living cells are the objectives of further research. Nevertheless, the experimental results obtained to date provide grounds for believing that pharmaceutical agents enriched in 25Mg and possibly in the magnetic isotopes of some other chemical elements will find use in biomedicine, for example, in cardiology for prevention and treatment of acute hypoxia, in oncology as cytostatics, and for the development of new antistress agents and radiation protectors.