title: Kinetics of the proton-deuteron exchange at position H8 of adenine and guanine in DNA.
abstract: Proton-NMR has been used to determine the activation energies and pre-exponential factors for the deuterium exchange of AH8 in poly(dA-dT).poly(dA-dT), and for GH8 in poly(dG-dC).poly(dG-dC). No simple relationship between the kinetic parameters and molecular conformation was found. By addition of 4.5 M NaCl a transition from the B to the Z conformation was induced for poly(dG-dC).poly(dG-dC), and an increased exchange rate was observed. The exchange rate for poly(dA-dT).poly(dA-dT) also increased below 64 degrees C, and a significant decrease in activation energy on addition of 4.5 M NaCl was observed. The exchange rates at T = 55.8 degrees C were also measured for the AH8 and GH8 in random sequence calf thymus DNA. From the difference in exchange rates, a method of preferential labeling of either the AH8 or the GH8 in high molecular weight DNA is evaluated.
mesh_terms: D000225:Adenine; D004247:DNA; D003903:Deuterium; D006147:Guanine; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D009690:Nucleic Acid Conformation; D011522:Protons; D012965:Sodium Chloride / Q000494:pharmacology; D013696:Temperature
chemical_list: D011522:Protons; D012965:Sodium Chloride; D006147:Guanine; D004247:DNA; D003903:Deuterium; D000225:Adenine