New horizons of adenosinetriphosphate energetics arising from interaction with magnesium cofactor.
MD DFT:B3LYP (6-31G** basis set, T = 310 K) method is used to study interactions [singlet (S) and triplet (T) reaction paths] between adenosinetriphosphate, ATP(4-), and [Mg(H(2)O)(6)](2+) in water environment, modeled with 78 water molecules. Computations reveal the appearance of low and high-energy states (stable, quasi-stable, and unstable), assigned to different spin symmetries. At the initial stage of interaction, ATP donates a part of its negative charge to the Mg complex making the Mg slightly charged. As a result, the original octahedral Mg complex loses two (S state) or four (T state) water molecules. Moving along S or T potential energy surfaces (PESs), Mg(H(2)O)(4 )or Mg(H(2)O)(2) display different ways of complexation with ATP. S path favors the formation of a stable chelate with the O1-O2 fragment of ATP triphosphate tail, whereas T path favors producing a single-bonded complex with the O2. The latter, being unstable, undergoes a further conversion into a spin-separated complex, also unstable, and two metastable S complexes, which finally arise in two stable, low-energy and high-energy, chelates. The spin-separated complex experiences rapid decomposition resulting in the production of a highly reactive adenosinemonophosphate ion-radical *AMP, early observed in the CIDNP experiment (Tulub 2006). Biological consequences of the findings are discussed.
Tulub
Alexander A
AA
Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA. atulub@yahoo.co.uk
Stefanov
V E
VE
D000255:Adenosine Triphosphate / Q000737:chemistry* / Q000378:metabolism*; D002614:Chelating Agents / Q000737:chemistry; D004583:Electrons; D008274:Magnesium / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D008968:Molecular Conformation; D010084:Oxidation-Reduction; D011789:Quantum Theory; D014867:Water / Q000737:chemistry
D002614:Chelating Agents; D014867:Water; D000255:Adenosine Triphosphate; D008274:Magnesium