title: DNA-sequence and metal-ion specificity of the formation of *H-DNA.
abstract: The homopyrimidine-homopurine sequence d(CT/GA)22 undergoes, in the presence of zinc ions, transition to an altered DNA conformation (*H-DNA) which is neither H-DNA nor B-DNA. *H-DNA is characterized by a peculiar chemical reactivity pattern in which most of the polypyrimidine strand is hyperreactive to osmium tetroxide and the central part of the polypurine strand is sensitive to diethylpyrocarbonate. Formation of *H-DNA is specific of metal-ion. *H-DNA is detected in the presence of Zn++, Cd++ and Mn++. The efficiency on promoting the transition is in the order of Zn++ greater than Cd++ much greater than Mn++. Formation of *H-DNA is also specific of nucleotide sequence. From all the different homopolymeric sequences tested only the d(CT/GA)22 sequence showed the zinc-induced transition to *H-DNA. These results suggest that stabilization of *H-DNA involves the formation of a specific complex between the metal-ion and the nucleotide sequence. The biological relevance of these results is discussed in view of the important role that zinc ions play on many nucleic acids processes.
authors.affiliation: Grupo de Química Macromolecular, Centro de Investigación y Desarrollo CSIC, ETSEIB, Barcelona, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Bernués
authors.forename: R
authors.initials: R
authors.lastname: Beltrán
authors.forename: J M
authors.initials: JM
authors.lastname: Casasnovas
authors.forename: F
authors.initials: F
authors.lastname: Azorín
mesh_terms: D001483:Base Sequence; D002104:Cadmium; D002118:Calcium; D003035:Cobalt; D003300:Copper; D004247:DNA; D008274:Magnesium; D008345:Manganese; D008969:Molecular Sequence Data; D009532:Nickel; D009690:Nucleic Acid Conformation; D015032:Zinc
chemical_list: D002104:Cadmium; D003035:Cobalt; D008345:Manganese; D003300:Copper; D009532:Nickel; D004247:DNA; D008274:Magnesium; D015032:Zinc; D002118:Calcium