[Correlation between conformation distortion of the DNA sugar-phosphate backbone and high optical activity of its compact form].
Different physico-chemical methods (CD, ORD, small-angle X-ray diffraction, etc) were used for investigating the properties of the DNA compact particles formed in PEG-containing water-salt solutions. It has been shown that small-angle reflection, characteristic of the DNA compact particles, changes from 36.8 A (CPEG = 140 mg/ml) to 25 A (CPEG = 300 mg/ml). The maximal optical activity (the intense negative CD-band and optical rotation [alpha] = 60 000 degrees) are inherent properties of the DNA compact particles formed at CPEG 120--180 mg/ml. The high optical activity points to the twist of DNA chromophores through the DNA molecule resulting in a long-rang pitch (P approximately 2000A). Such macroscopic superhelical structure (diameter 40--30 A) is due to conformational distortion of the DNA double-helix with alternating "left" and "right" orientation of chromophoes. Disappearance of conformation distortion is accompanied by disappearance of the high optical activity of the DNA compact particles and results in a small-angle reflection of 25 A. Taking into account the reasons of formation of the optically-active DNA compact particles conditions are suggested to conserve high optical activity at CPEG equal to 400 mg/ml.
D002942:Circular Dichroism; D004247:DNA; D009690:Nucleic Acid Conformation; D009905:Optical Rotatory Dispersion; D014961:X-Ray Diffraction
D004247:DNA
O sviazi mezhdu konformatsionnoĭ neodnorodnost'iu struktury dvukhtsepochechnoĭ DNK i vysokoĭ opticheskoĭ aktivnost'iu ee kompaktnoĭ formy.