[Effect of temperature on the acid-base equilibrium in a DNA molecule].

The influence of temperature on structural transitions in a protonated DNA molecule has been studied by means of circular dichroism (CD). The measurements were carried at continuos heating over a temperature range from 288 to 343 K at an average rate of (15-30) x 10(-4) K/sec. The objects were diluted DNA solutions (30.

[Polyelectrolyte invariance of the acid-base equilibrium in native DNA with varying GC-pair levels].

The influence of the ionic strength of solution on the protonation of the Micrococcus lysodeicticus DNA molecule was studied by means of circular dichroism, spectrophotometric and potentiometric titration in a wide range of the supporting electrolyte concentration ([NaCl] = 0.5-0.005 M).

[The effect of spermine on acid-base equilibrium in DNA molecule].

The influence of spermine (Sp) on the acid-induced predenaturational and denaturational transitions in the DNA molecule structure has been studied by means of circular dichroism, spectrophotometric and viscometric titration at supporting electrolyte concentration 10 mM NaCl. The data available indicate that at [N]/[P] less than or equal to 0.60 (here [N] and [P] are molar concentrations of Sp nitrogen and DNA phosphours, respectively) the cooperative structural B----B(+)----S transitions are accompanied by the DNA double-helice winding.

[Differential scattering of circularly polarized light in protonated DNA in the presence of spermine].

The protonation of the spermine containing calf thymus DNA (molecular mass 15 and 5 MDa) solutions has been studied by means of circular dichroism method. It has been shown that the acid-induced transition from the low-protonated B(+)-form to the double-stranded structure with presumably Hoogsteen complementation of syn-G.C-base-pairs (S-form) in case of high-molecular partially condensed DNA is accompanied by differential scattering of circularly polarized light (DSCPL).

[Binding of polyamines by the double-helical DNA molecule in unfolded and compact forms].

The influence of the natural polyamines [spermine (Sp) and spermidine (Spd)] on the conformation of thymus DNA molecule (M = 4 and 15 MDa) was studied by means of the viscometric method over the range of low supporting electrolyte concentrations (CNaCl = 0.6 divided by 8.4 mM).