A Nuclear Spin Selective Control over the DNA Repair Key Enzyme Might Renovate the Cancer–Fight Paradigm. DNA Polymerase Beta to Engage with a Magnetic Isotope Effect

DNA Polymerase Beta (EC 2.7.7.7) is found to be operated by magnetic isotope effect (MIE) of Calcium once the Mg2+ ions replaced with the stable 43Ca2+ isotopes inside the enzyme catalytic sites. The isotope mentioned is the only paramagnetic species of the Calcium isotopic set with a 0.135 natural abundance value and the negative 7/2 nuclear spin providing a nuclear magnetic moment equal to 1.317 Bohr magnetons. As compared to the Mg/40Ca substitution, a 2.25-fold enzyme inhibition has been shown to provethe43Ca-MIE dependent mode of the catalysis turning down.An ion-radical mechanism based on the singlet – triplet conversion of the enzyme generated intermediates (ion-radical pairs) is found to be engaged once the paramagnetic metal isotope involved into the catalysis studied.The MIE promotes a primary reaction in DNA synthesis constituting in electron transfer between the ion – radical forming partners, [Ca(H2O)n2+] and [Ca2+(dNTP)]. Once the metal isotope substitution takes place inside just one of two DNA Polymerase Beta catalytic sites, a consequent43Ca – promoted inhibition leads to a residual synthesis of shorted DNA fragments that counts 25 – 35 nucleotides in length contrasting with the 180n – 210n DNA produced by either intact or40Ca – loaded polymerase. Being occurred simultaneously with a marked MIE – promoted enzyme inhibition, this fact itself makes possible to consider these short (“size-invalidâ€) DNA segments hardly efficient in the DNA base – excision repair. The latter is a survival factor in leukemic cells where the DNApolβ was found overexpressed. That supports a standpoint considering theDNApolβ a legitimate target for antitumor agents since its inhibition deprives the malignant cell from a DNA base – excision repair in neoplasma. A possible trend making role of these data in the current developments on a novel concept - establishing chemical background for cancer therapies is in a focus

A Nuclear Magnetic Insight Towards the Cytostatic Potential of Medicinal Plant Extracts Replay to Al Wihibi et al Biomedica 2019;35(4):203-209

Cytostatic activities of water and organic extracts prepared from medicinal higher plants including Ducrosia anethifolia should be analyzed by taking into account the &ldquo;hidden&rdquo; magnetic isotope effects of stable metal isotopes (25Mg, 43Ca, 67Zn &hellip;) pre-(bio) fractionated in the plant tissues. A multi-collector inductively coupled plasma mass spectrometry (MC &ndash; ICPMS) might be successfully employed to reveal and detail this specific peculiarity for further pharmacological applications.</p

In Silico Studies on Pharmacokinetics and Neuroprotective Potential of ²⁵Mg²⁺: Releasing Nanocationites - Background and Perspectives

Sharp blood circulation disorders are known for their capability to promote such abundant and hardly treatable pathologies as myocardium infarction and the ischemic brain stroke (“insult”). Noteworthy, the stroke — related brain tissue metabolic damages involve an essential ATP deplete clash along with a suppression of brain specific nucleotide — associated kinases and ATP synthase, both Mg2+ — dependent complex enzyme “machineries”. This itself makes the latter’s a legitimate target for some advanced pharmaceuticals as long as the drug — induced overstimulation of corresponding enzymatic activity is the case. Thus, magnetic isotope effects (MIE) of the nuclear spin possessing paramagnetic 25Mg2+ ions might modulate the brain creatine kinase, alfa-glycerophosphate kinase and pyruvate kinase catalytic activities in a way of a remarkable ATP hyperproduction required to compensate the hypoxia caused acute metabolic breakdown. To realize the Magnesium-25 pharmacological potential, a low-toxic amphiphilic cationite nanoparticles were introduced lately. Particularly, the Magnesium — releasing porphyrin-fullerene nanoadduct (cyclohexyl-C60-porphyrin, PMC16) has been proposed to meet expectations dealing with a targeted delivery of 25Mg2+ towards the brain ischemia surrounding areas. In order to optimize a multi-step [25Mg2+]4PMC16 preclinical trial scenario, the In Silico algorithms are to be developed and analyzed. In this study, these algorithms are in a focus with a special emphasize on a novel combination of slightly modified Gompertzian equation systems and a non-Markov population dynamics concept. This In Silico approach takes into account some literature-available patterns of brain hypoxia pathogenesis, the resulted simulation model could be considered as a promising tool for further research on experimental nanopharmacology of the ischemic stroke

Retinoblastoma: Magnetic Isotope Effects Might Make a Difference in the Current Anti-Cancer Research Strategy

Human retinoblastoma cells were proven to possess some very unusual DNApolβ species. Being 23.5 kDa monomers, which itself is not common for the DNApolβ superfamily members, these chromatin associated proteins manifests most of the DNApolβ-specifc functional peculiarities making them legitimate targets for DNA repair cytostatic inhibitors. Particularly, these tumor specific enzymes were found to be very sensitive to 25Mg2+-, 43Ca2+- and 67Zn2+-promoted magnetic isotope effects (MIE) caused a marked DNA sequence growth limitation as well as a formation of the size-invalid, i.e. too short in length, DNA fragments, totally inappropriate for the DNA repair purpose. This MIE-DNApolβ match may serve a starting point for further move towards the paramagnetic path in current developments of anti-cancer strategies

Magnetic field and nuclear spin influence on the DNA synthesis rate

Abstract The rate of a chemical reaction can be sensitive to the isotope composition of the reactants, which provides also for the sensitivity of such “spin-sensitive” reactions to the external magnetic field. Here we demonstrate the effect of the external magnetic field on the enzymatic DNA synthesis together with the effect of the spin-bearing magnesium ions ( $$^{25}$$ 25 Mg). The rate of DNA synthesis monotonously decreased with the external magnetic field induction increasing in presence of zero-spin magnesium ions ( $$^{24}$$ 24 Mg). On the contrary, in the presence of the spin-bearing magnesium ions, the dependence of the reaction rate on the magnetic field induction was non-monotonous and possess a distinct minimum at 80–100 mT. To describe the observed effect, we suggested a chemical scheme and biophysical mechanism considering a competition between Zeeman and Fermi interactions in the external magnetic field

Anti-cancer activity of ultra-short single-stranded polydeoxyribonucleotides

Summary One of the features that differentiate cancer cells is their increased proliferation rate, which creates an opportunity for general anti-tumor therapy directed against the elevated activity of replicative apparatus in tumor cells. Besides DNA synthesis, successful genome replication requires the reparation of the newly synthesized DNA. Malfunctions in reparation can cause fatal injuries in the genome and cell death. Recently we have found that the ultra-short single-stranded deoxyribose polynucleotides of random sequence (ssDNA) effectively inhibit the catalytic activity of DNA polymerase $$\beta$$ β . This effect allowed considering these substances as potential anti-tumor drugs, which was confirmed experimentally both in vitro (using cancer cell cultures) and in vivo (using cancer models in mice). According to the obtained results, ssDNA significantly suppresses cancer development and tumor growth, allowing consideration of them as novel candidates for anti-cancer drugs