Nordén B
Biophys Chem. 1976 Dec;6(1):31-45. doi: 10.1016/0301-4622(76)80059-2.
Linear dichroism (LD) results when pseudoisocyanine=PIC (1,1-diethy1-2,2-cyannine iodide) binds to flow-oriented DNA. LD may be used to follow the complexation both stoichmetrically and structurally, since when specified to unti complex concentration LD provides a measure of the average orientation of the absorbing transition dipole. Two different types of complexes can be distinguished: I. One strong, ionic-strength insensitive complex with monomeric PIC with an orientation indication intercalation. II. Several weaker complexes of electrostatic nature (only observed at I less than 0.2M Na Cl) among which those with dimeric (IIa) and with polymeric (IIb) PIC are concluded both from LD and from circular dichroism (CD). The dimer is probably formed by employing one intercalated PIC as a second site. The polymer complex is characterized by a very sharp absorption band at 553 nm polarized parallel to the DNA-axis (with positive LD and positive CL). The structure, a right-handed helical array of PIC molecules, is discussed in terms of exciton theory in relation to that of polymeric free PIC ("Scheibe polymer") which is also shown to interact with DNA (IIc) yielding a large aggregate which is degraded at a distinct flow force field...
当假异氰吲哚（PIC，1,1 - 二乙基 - 2,2 - 氰基碘化吲哚）与流动取向的DNA结合时会产生线性二色性（LD）。LD可用于从化学计量和结构两方面追踪复合物的形成，因为当指定到单位复合物浓度时，LD可提供吸收跃迁偶极平均取向的一种度量。可以区分出两种不同类型的复合物：I. 一种与单体PIC形成的强的、对离子强度不敏感的复合物，其取向表明存在嵌入作用。II. 几种静电性质的较弱复合物（仅在氯化钠浓度小于0.2M时观察到），其中二聚体（IIa）和多聚体（IIb）PIC形成的复合物可通过LD和圆二色性（CD）得出结论。二聚体可能是通过将一个嵌入的PIC用作第二个位点形成的。聚合物复合物的特征是在553nm处有一个非常尖锐的吸收带，其偏振方向平行于DNA轴（具有正的LD和正的CL）。根据激子理论，讨论了PIC分子的右手螺旋阵列结构与多聚游离PIC（“谢贝聚合物”）的结构的关系，多聚游离PIC也被证明与DNA相互作用（IIc），产生一个大的聚集体，该聚集体在一个特定的流动力场中会降解……
