title: [Bis-(2-guanidoethyl)-disulfide, when complexed with DNA, prevents its winding within the B-family].
abstract: Earlier we have shown that DNA forms stoichiometric complexes with bis-(2-guanidoethyl)-disulfide (GED), the helix being transformed from the B-like structure into the C-like one. The present work demonstrates that the DNA helix in the saturated complex does not change its conformation within a broad range of conditions: 0 less than [NaCl] less than 5.10(-2) M; 0% less than [methanol] less than 60% (v/v); 5 degrees less than temperature less than 50 degrees. Free DNA undergoes a non-cooperative winding within the B-family under all these influences. Increase in NaCl concentration beyond 5.10(-2) M results in abrupt cooperative unwinding from the C-like form to the B-like one, apparently due to GED dissociation. The obtained data are in accord with the idea that the conformational transition of DNA within the B-family is induced by change of phosphates interaction with the hydrated cations of alcaline metals; formation of strong hydrogen bonds of the phosphates with GED makes the DNA helix non-sensitive to variations of the environment.
mesh_terms: D004247:DNA; D004220:Disulfides; D006146:Guanidines; D007700:Kinetics; D000432:Methanol; D009691:Nucleic Acid Denaturation; D009994:Osmolar Concentration; D012965:Sodium Chloride
chemical_list: D004220:Disulfides; D006146:Guanidines; D012965:Sodium Chloride; D004247:DNA; D000432:Methanol
vernacular_title: Kompleksiruias' s DNK, bis-(-2-guanidoétil)-disul'fid prepiatstvuet konformatsionnomu perek odu v b-semeĭstve.