nuclear magnetic resonance spectra ( proton and phosphorus-31 ) and ultraviolet absorption spectra of the dna decamer d ( br5cgbr5cgatbr5cgbr5cg ) , in which the central two adenine-thymine base pairs are out of order with the rest of the purine-pyrimidine alternation sequence , indicate that under appropriate solvent conditions ( high salt and methanol ) the molecule undergoes a structural transition from a right-handed b-dna conformation to a left-handed z-dna conformation .
C0001407
adenine
C0034140
purine