title: Spin biochemistry: magnetic 24Mg-25Mg-26Mg isotope effect in mitochondrial ADP phosphorylation.
abstract: The rates of adenosine triphosphate (ATP) production by isolated mitochondria and mitochondrial creatine kinase incubated in isotopically pure media containing, separately, (24)Mg(2+), (25)Mg(2+), and (26)Mg(2+) ions were shown to be strongly dependent on the magnesium nuclear spin and magnetic moment. The rate of adenosine 5'-diphosphate phosphorylation in mitochondria with magnetic nuclei (25)Mg is about twice higher than that with the spinless, nonmagnetic nuclei (24,26)Mg. When mitochondrial oxidative phosphorylation was selectively blocked by treatment with 1-methylnicotine amide, (25)Mg(2+) ions were shown to be nearly four times more active in mitochondrial ATP synthesis than (24,26)Mg(2+) ions. The rate of ATP production associated with creatine kinase is twice higher for (25)Mg(2+) than for (24,26)Mg and does not depend on the blockade of oxidative phosphorylation. There is no difference between (24)Mg(2+) and (26)Mg(2+) effects in both oxidative and substrate phosphorylation. These observations demonstrate that the enzymatic phosphorylation is a nuclear spin selective process controlled by magnetic isotope effect. The reaction mechanism proposed includes a participation of intermediate ion-radical pairs with Mg(+) cation as a radical partner. Therefore, the key mitochondrial phosphotransferases work as a magnesium nuclear spin mediated molecular machines.
authors.affiliation: NN Semenov Institute for Chemical Physics, Russian Academy of Sciences, Moscow. spinchem@chph.ras.ru
authors.forename: Anatoly L
authors.initials: AL
authors.lastname: Buchachenko
authors.forename: Dmitri A
authors.initials: DA
authors.lastname: Kouznetsov
authors.forename: Stanislav E
authors.initials: SE
authors.lastname: Arkhangelsky
authors.forename: Marina A
authors.initials: MA
authors.lastname: Orlova
authors.forename: Artyom A
authors.initials: AA
authors.lastname: Markarian
mesh_terms: D000244:Adenosine Diphosphate / Q000737:chemistry / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D001671:Biochemistry / Q000379:methods; D002478:Cells, Cultured; D007554:Isotopes / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D008274:Magnesium / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D008297:Male; D008929:Mitochondria, Heart / Q000378:metabolism*; D008954:Models, Biological; D008956:Models, Chemical; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D010766:Phosphorylation; D011865:Radioisotope Dilution Technique; D051381:Rats; D013113:Spin Labels
chemical_list: D007554:Isotopes; D013113:Spin Labels; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D008274:Magnesium