Diepoxybutane forms a monoadduct with B-form (dG-dC)n.(dG-dC)n and a crosslinked diadduct with the left-handed Z-form.

AUTOR(ES)

Kang, D S

RESUMO

The characteristics of the reactions of DL-diepoxybutane (DEB) with (dG-dC)n.(dG-dC)n in the right-handed B-form or the left-handed Z-form were investigated. DEB does react with right-handed B-DNA since less salt is required to convert the modified B-form to Z-form than for the unmodified DNA. However, the product appears to be a monoadduct rather than the crosslinked diadduct formed with the Z-form. The modified B-form can be isolated, converted to a Z-form with l mM MnCl2, and then this activated complex further reacts intramolecularly to give the crosslinked Z-product. This modified Z-form cannot be reverted to the B-form unless the crosslink is cleaved with periodate. Only MnCl2, and to a lesser extent ZnCl2, was effective in facilitating the intramolecular conversion of the B-DNA monoadduct to the Z-DNA diadduct; lmM MgCl2 and 4M NaCl were ineffective suggesting that somewhat different types of modified left-handed conformations were generated by the different salts. DEB also cleaves DNA under our reaction conditions thus precluding studies with supercoiled recombinant plasmids harboring segments that adopt Z-structures.

Documentos Relacionados

• The sequence (dC-dA)n X (dG-dT)n forms left-handed Z-DNA in negatively supercoiled plasmids.
• The tetraribonucleotide rCpGpCpG forms a left-handed Z-RNA double-helix.
• Z* DNA, the left-handed helical form of poly[d(G-C)] in MgCl2-ethanol, is biologically active.
• The high salt form of poly(dG-dC).poly(dG-dC) is left-handed Z-DNA: Raman spectra of crystals and solutions.
• A left-handed (Z) conformation of poly(dA-dC).poly(dG-dT) induced by polyamines.