A comparative X-ray diffraction and circular dichroism study of DNA compact particles formed in water-salt solutions, containing poly(ediylene glycol)

• Published in: Nucleic acids research 1976-09, Vol.3 (9), p.2353-2366
• Main Authors: Evdokimov, Yu.M., Pyatigorskaya, T.L., Polyvtsev, O.F., Akimenko, N.M., Kadykov, V.A., Tsvankin, D.Ya, Varshavsky, Ya.M.
• Format: Article
• Language: English
• Subjects: Circular Dichroism; DNA, Bacterial; Escherichia coli; Nucleic Acid Conformation; Nucleic Acid Denaturation; Polyethylene Glycols; X-Ray Diffraction
• ISSN: 0305-1048; 1362-4962
• DOI: 10.1093/nar/3.9.2353

Comparative CD and X-ray diffraction studies of DNA compact particules which were obtained in PEG-containing water-salt solutions, have been carried out. Compact particules, formed from native DNA, produce a ψ CD spectrum (characterized by a negative band at λ∼27O nm) and a small-angle Xray diffraction pattern, which shows two reflections: I at 34–40 Å and II at 80–90 Å (together with its second-order reflection). Compact particules, formed from DNA molecules with partially disordered secondary structure, do not produce the ψ CD spectrum and the reflection I, while theQreflection II remains unchanged. It is suggested that the spacing of 34–40 Å is associated with a side-by-side packing of DNA fragments in “microcrystalline” regions in compact particules and that such “microcrystallizatlon” accounts for the generation of the ψ CD spectrum.