Giartosio A, Ferraro A, Lavaggi M V, Allegra P, Turano C
Physiol Chem Phys Med NMR. 1984;16(6):481-90.
The interaction of bisbenzimide (Hoechst 33258) with DNA has been studied by microcalorimetry, fluorimetry and fluorescence polarization measurements. The binding does not involve intercalation, takes place in at least two modes and occurs in the major groove at low dye/DNA molar ratio (first mode of binding), in agreement with previous proposals by other Authors. Furthermore it has been shown that i) at high dye/DNA molar ratio the binding (second mode) occurs in both grooves; ii) at pH 7.0 the protonation of a dye nitrogen accompanies the binding in both modes; iii) the quantum yield of the dye-DNA complex is sensitive to the DNA conformation change caused by an increase in ionic strength. Basically the same type of binding takes place on chromatin, as detected by calorimetry. However, at high dye/DNA molar ratio about 30% of DNA is not accessible to the dye. The decreased accessibility appears to be mainly related to the nucleosomal structure of chromatin.
已通过微量热法、荧光法和荧光偏振测量研究了双苯甲酰亚胺（Hoechst 33258）与DNA的相互作用。这种结合不涉及嵌入，至少以两种模式发生，并且在低染料/DNA摩尔比时发生在大沟中（第一种结合模式），这与其他作者先前的提议一致。此外，研究表明：i）在高染料/DNA摩尔比时，结合（第二种模式）在两条沟中都发生；ii）在pH 7.0时，染料氮的质子化在两种模式的结合过程中都会发生；iii）染料-DNA复合物的量子产率对离子强度增加引起的DNA构象变化敏感。通过量热法检测发现，染色质上发生的结合基本属于同一类型。然而，在高染料/DNA摩尔比时，约30%的DNA无法与染料结合。可及性降低似乎主要与染色质的核小体结构有关。
