Tselikova S B, Lobachev V M, Ivanov V I
Mol Biol (Mosk). 1979 Jan-Feb;13(1):180-3.
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.
早些时候我们已经表明，DNA与双（2-胍基乙基）二硫化物（GED）形成化学计量复合物，螺旋结构从类B结构转变为类C结构。目前的工作表明，饱和复合物中的DNA螺旋在很宽的条件范围内不会改变其构象：0＜[NaCl]＜5×10⁻²M；0%＜[甲醇]＜60%（v/v）；5℃＜温度＜50℃。在所有这些影响下，游离DNA在B族内进行非协同缠绕。NaCl浓度增加超过5×10⁻²M会导致从类C形式突然协同解旋为类B形式，这显然是由于GED解离。所获得的数据符合以下观点：DNA在B族内的构象转变是由磷酸盐与碱金属水合阳离子相互作用的变化引起的；磷酸盐与GED形成强氢键使DNA螺旋对环境变化不敏感。
