Study of Metalhyphen;Ion Binding to Nucleic Acids by31P Nuclear Magnetic Resonance

摘要

We have measured the31P NMR in aqueous solutions of RNA (ribonucleic acid) and AMP (adenosine monophosphate) containing Mn2+and Co2+ions. Measurements ofT1,T2, and Dgr;ohgr;, the shift from ggr;IH0, were made as functions of the metalhyphen;ion concentration and the temperature. Nearhyphen;roomhyphen;temperature linewidths were determined by the slow chemical exchange. At higher temperatures the Co2+complexes enter the exchangehyphen;narrowed region where31P shifts in the CoAMP system are observed.The roomhyphen;temperature value ofT1for CoAMP and CoRNA complexes, the highhyphen;temperature shifts of the CoAMP, and the highhyphen;temperature values ofT2in the MnAMP all independently determine the strength of the isotropic transferred hyperfine couplingAbetween the metal ions and the31P nuclei. Within the experimental accuracy which ranges from sim;5 (for Dgr;ohgr;) to sim;50 (forT1measurements) the values ofAagreed with the values derived from31P NMR measurements in crystals of Mn3(PO4)2and Co3(PO4)2. From the similarity ofAin crystals and complexes, we conclude that Mn2+and Co2+bind to the phosphates of AMP and RNA.