Isotope Effects Induced by Molecular Compression.

Zero-point energies (ZPEs) of hydroxyl ion and hydrogen and water molecules, free and compressed in C cages, are computed; the excess energy acquired by molecules under compression is in the range 2-3 kcal/mol and depends on the isotopes. The differences in ZPE of compressed isotopic molecules strongly exceed those of the free molecules, resulting in the large deuterium and tritium isotope effects. These effects induced by compression are suggested as a probe for testing molecular compression of enzymatic sites; they may be important for understanding enormously large isotope effects observed in some enzymatic reactions, where they are attributed to the tunneling.

Magnetic isotope and magnetic field effects on the DNA synthesis.

Magnetic isotope and magnetic field effects on the rate of DNA synthesis catalysed by polymerases β with isotopic ions (24)Mg(2+), (25)Mg(2+) and (26)Mg(2+) in the catalytic sites were detected. No difference in enzymatic activity was found between polymerases β carrying (24)Mg(2+) and (26)Mg(2+) ions with spinless, non-magnetic nuclei (24)Mg and (26)Mg. However, (25)Mg(2+) ions with magnetic nucleus (25)Mg were shown to suppress enzymatic activity by two to three times with respect to the enzymatic activity of polymerases β with (24)Mg(2+) and (26)Mg(2+) ions.

Ion-radical mechanism of enzymatic ATP synthesis: DFT calculations and experimental control.

A new, ion-radical mechanism of enzymatic ATP synthesis was recently discovered by using magnesium isotopes. It functions at a high concentration of MgCl(2) and includes electron transfer from the Mg(H(2)O)(m)(2+)(ADP(3-)) complex (m = 0-4) to the Mg(H(2)O)(n)(2+) complex as a primary reaction of ATP synthesis in catalytic sites of ATP synthase and kinases. Here, the structures and electron transfer reaction energies of magnesium complexes related to ATP synthesis are calculated in terms of DFT.

Magnesium isotope effects in enzymatic phosphorylation.

Recent discovery of magnesium isotope effect in the rate of enzymatic synthesis of adenosine triphosphate (ATP) offers a new insight into the mechanochemistry of enzymes as the molecular machines. The activity of phosphorylating enzymes (ATP-synthase, phosphocreatine, and phosphoglycerate kinases) in which Mg(2+) ion has a magnetic isotopic nucleus 25Mg was found to be 2-3 times higher than that of enzymes in which Mg(2+) ion has spinless, nonmagnetic isotopic nuclei 24Mg or 26Mg. This isotope effect demonstrates unambiguously that the ATP synthesis is a spin-dependent ion-radical process.