Crystal structure of Z-DNA without an alternating purine-pyrimidine sequence.
In left-handed Z-DNA, consecutive nucleotides along the chain alternate in the syn and anti conformations. Purine residues form the syn conformation readily and up to now all Z-DNA crystal structures have sequences of alternating purines and pyrimidines. However, we find that d(C-G-A-T-C-G) with the cytosines brominated or methylated on C-5 crystallizes as Z-DNA. The structure reveals thymines in syn and adenines in anti conformations. This suggests that Z-DNA may occur in sequences other than those with alternating purine-pyrimidine sequence.
D001483:Base Sequence; D003460:Crystallization; D004247:DNA; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D014961:X-Ray Diffraction
D004247:DNA