Magnetic 25Mg Research Articles

Ribulose 1,5-bisphosphate carboxylase/oxygenase activates O2 by electron transfer

Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) is the cornerstone of atmospheric CO2 fixation by the biosphere. It catalyzes the addition of CO2 onto enolized ribulose 1,5-bisphosphate (RuBP), producing 3-phosphoglycerate which is then converted to sugars. The major problem of this reaction is competitive O2 addition, which forms a phosphorylated product (2-phosphoglycolate) that must be recycled by a series of biochemical reactions (photorespiratory metabolism). However, the way the enzyme activates O2 is still unknown. Here, we used isotope effects (with 2H, 25Mg, and 18O) to monitor O2 activation and assess the influence of outer sphere atoms, in two Rubisco forms of contrasted O2/CO2 selectivity. Neither the Rubisco form nor the use of solvent D2O and deuterated RuBP changed the 16O/18O isotope effect of O2 addition, in clear contrast with the 12C/13C isotope effect of CO2 addition. Furthermore, substitution of light magnesium (24Mg) by heavy, nuclear magnetic 25Mg had no effect on O2 addition. Therefore, outer sphere protons have no influence on the reaction and direct radical chemistry (intersystem crossing with triplet O2) does not seem to be involved in O2 activation. Computations indicate that the reduction potential of enolized RuBP (near 0.49 V) is compatible with superoxide (O2•-) production, must be insensitive to deuteration, and yields a predicted 16O/18O isotope effect and energy barrier close to observed values. Overall, O2 undergoes single electron transfer to form short-lived superoxide, which then recombines to form a peroxide intermediate.

Combined effect of magnesium isotopes and antibiotics on morphology of E. coli

In this paper, the morphology of Escherichia coli bacteria grown in the presence of magnesium isotopes (magnetic 25Mg, non-magnetic 24,26Mg and natural Mg), and antibiotics of various groups were studied. Atomic force microscopy (AFM) was used as the main method. When the bacteria were cultured in the presence of different groups of antibiotics, the following morphological changes were detected: filamentation, cell lysis, cell adhesion, cell wall damage, and the formation of “depressions” or pores. For E. coli bacteria cultured on a medium with tobramycin and lincomycin, a magnetic magnesium isotope effect 25Mg in bacteria morphology was detected, which was manifested as a change in the roughness of bacterial cells. Both of these antibacterial drugs act on the same intracellular system – protein synthesis. It has also been observed that the elongation of bacterial cells, when exposed to levofloxacin and ciprofloxacin, depends on the type of magnesium isotope in the nutrient medium. The combined action of the 25Mg magnetic isotope and quinolones on bacteria makes it possible to obtain the process followed by significant elongation of cells, thereby indicating improved antibiotic effect, as compared with the nonmagnetic 24,26Mg isotopes.

Firefly Luciferase Bioluminescence as a Tool for Searching Magnetic Isotope Effects in ATP-Dependent Enzyme Reactions

Cells and tissues are composed from atoms of chemical elements, some of which have two kinds of stable isotopes, magnetic and nonmagnetic ones. Not long ago, magnetic isotope effects (MIEs) have been discovered in experiments with cells enriched with magnetic or nonmagnetic isotopes of magnesium. These MIEs can stem from higher efficiency of the enzymes of bioenergetics in the cells enriched with magnetic magnesium isotope. In the studies of MIEs in biological systems, it is needed to monitor the ATP concentrations as the major energy source in cells. The most sensitive and rapid method of the ATP measurements is based on the use of the firefly luciferase–luciferin system. Since luciferase is the ATP-dependent enzyme and activated by Mg-ions, it is necessary to elucidate whether this enzyme is sensitive to magnetic field of the magnesium isotope’s nuclear spin. Herein we present the results of studying the effects of different isotopes of magnesium, magnetic 25Mg and nonmagnetic 24Mg and 26Mg, on bioluminescence spectra and enzymatic activity of firefly luciferase. It was shown, that neither kinetics of the bioluminescence signal nor the bioluminescence spectra manifest any statistically significant dependence on the type of magnesium isotope. So, no MIEs have been revealed in the luciferase-catalyzed oxidation of luciferin. It means that firefly luciferase bioluminescence can serve as the tool for search and studies of magnetic isotope effects in ATP-dependent enzyme reactions in biological systems, including the enzymatic synthesis and hydrolysis of ATP.

Nuclear spin catalysis in living nature

Experiments with cells enriched in stable magnesium isotopes, magnetic 25Mg or nonmagnetic 24Mg and 26Mg, are carried out. It is revealed that adaptation of bacteria E. coli to the growth media enriched in magnetic 25Mg proceeds faster as compared to the growth media enriched in nonmagnetic magnesium isotopes. In experiments with another commonly accepted cell model, S. cerevisiae yeast, it is revealed that the rate constant of postradiation recovery of the cells after UV irradiation is two times higher for cells enriched in 25Mg than for cells enriched in the nonmagnetic isotope. In collaboration with Ukrainian colleagues from the Palladin Institute of Biochemistry, the effects of different isotopes of magnesium on ATPase activity of myosin isolated from myometrium are studied. It is found that the rate of the enzymatic hydrolysis of ATP for 25Mg is 2.0–2.5 times higher as compared to nonmagnetic isotopes 24Mg and 26Mg. Some possible mechanisms of magnetic isotope effects (nuclear spin catalysis) in biological objects are discussed.

Magnetic isotope of magnesium accelerates ATP hydrolysis catalyzed by myosin

In this paper, we present the results of experimental studies on the influence of different magnesium isotopes, magnetic 25Mg and nonmagnetic 24Mg or 26Mg, on ATP-hydrolytic activity of the isolated myosin subfragment-1. The reaction rate in the presence of magnetic 25Mg isotope turned out to be 2.0–2.5 times higher than that using non-magnetic 24Mg or 26Mg isotopes. In absence of the enzyme, as at spontaneous ATP hydrolysis in aqueous solution, no magnetic isotope effect was observed. Thus, a significant catalytic effect of the magnetic 25Mg isotope (nuclear spin catalysis) was discovered in the enzymatic hydrolysis of ATP.

Stable magnetic isotopes: from spin chemistry to biomedicine

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.

Nuclear spin catalysis in nanoreactors of living cells

There is a great variety of chemical elements with magnetic and nonmagnetic isotopes in living cells. The question arises as to whether living cells can perceive the difference between magnetic and non-magnetic isotopes of chemical elements. It has been shown that bacteria Escherichia coli, which were previously enriched with the magnetic isotope of magnesium, 25Mg, essentially faster adapt to the new growth media in comparison with the cells, which were enriched with the nonmagnetic isotopes, 24Mg or 26Mg. In the experiments with another commonly accepted cell model, yeast Saccharomyces cerevisiae, it has been shown that the magnetic 25Mg, in comparison with the nonmagnetic 24Mg, essentially better stimulates recovery of the cells after short wave UV irradiation. Thus, for the first time, the magnetic isotope effects in vivo have been discovered. These findings reveal the novel, based on the stable magnetic isotopes, ways of control over efficiency and reliability of biological systems.