Methodology And Application Of Nuclear Magnetic Resonance On ATP Molecular Dynamics

Adenosine-5'-triphophate (ATP) is the very important biochemical compound involved in many biochemical processes. Studies on ATP have aroused much attention. In this thesis, methodology and application of nuclear magnetic resonance on ATP interaction with other molecules have been studied. This dissertation covers the following content.1 .Interaction of ATP with metal ions Fe³⁺ and Zn²⁺Relaxation rate and chemical shift are very sensitive to change of chemical surroundings. In our systems of Fe³⁺ and ATP solutions, we were able to calculate the relative distances between the NMR active nuclei (¹H and ³¹P) and the paramagnetic ion Fe³⁺ based on the theory of D-D interaction. We found for the first time that the coordination sites of ATP to Fe³⁺ strongly depend on pH of solution: Nl at lower pH(<4.5) and N7 at higher pH(between 5.5 and 7.5), while at pH 5.25 ATP binds Fe³⁺ with the purine Ï€ electrons to form a Ï€-complex.In solutions of equally molar zinc chloride and ATP, we found that Zn²⁺ induced large chemical shifts (>10 ppm) for Nl at lower pH (2-5) while for N7 at higher pH (5-7). These phenomena suggest that the binding site of Zn²⁺ in the purine base of ATP is Nl at low pH and N7 at high pH and contrast to the adenosine-Zn²⁺ system where the purine base binds Zn²⁺ with N7 at low pH while with Nl at high pH. We suppose that the tri-phosphates play a key role in the structure of ATP complex with metal ion such as Fe³⁺ or Zn²⁺.We give unambiguous evidences of N-1 coordinating to metal ions and challenge the well accepted concept that metal ions coordinated only to the phosphate chain with N-7 but not with N-1.2. Hydrolysis by model compounds of purple acid phosphatase and damage byFe²⁺ and H₂O₂.