UV light-induced crosslinking of the strands of poly(dA-dT) and related alternating purine-pyrimidine DNAs.
Alkaline agarose gel electrophoresis was used to detect UV-induced crosslinking of the strands of poly(dA-dT) and related alternating purine-pyrimidine DNAs in solutions stabilizing various polynucleotide conformations. Strands of the B-form and A-form of poly(dA-dT) were not crosslinked but a UV dose-dependent retarded species appeared in the denaturing gels in parallel with the polynucleotide isomerization into the unusual X-form. Most other polynucleotides adopting the X-form were crosslinked as well. The exceptions include the X-forms of poly(dA-butyl5dU) and poly(dA-pentyl5dU) whose strands do not crosslink because the long exocyclic substituents attached to uracil make the photodimerization impossible. Strands of poly(amino2dA-dT) and poly(dA, amino2dA-dT), the latter polynucleotide containing roughly equal amounts of amino2adenine and adenine, also do not crosslink upon UV irradiation because they isomerize into an A-like conformation which is different from the X-form of poly (dA-dT). In contrast, strands of the mixed copolymers of poly(dA, amino2dA-dT) containing low amino2adenine contents are crosslinked upon UV irradiation, in accordance with the observation that they isomerize into the X-form.
Kypr
J
J
Institute of Biophysics, Czech Academy of Sciences, Brno.
Penázová
H
H
Sági
J
J
Pospísilová
S
S
Vorlícková
M
M
D004587:Electrophoresis, Agar Gel; D006863:Hydrogen-Ion Concentration; D009690:Nucleic Acid Conformation / Q000187:drug effects*; D009691:Nucleic Acid Denaturation; D011067:Poly dA-dT / Q000737:chemistry* / Q000528:radiation effects; D011089:Polydeoxyribonucleotides / Q000737:chemistry*; D014466:Ultraviolet Rays
D011089:Polydeoxyribonucleotides; D011067:Poly dA-dT