A STUDY OF THE SELF-ASSEMBLY OF 2'-DEOXYGUANYLYL-(3'-]5')-2'-DEOXYGUANOSINE, D(GPG), BY SAXS AND CD

The title compound in water, with or without added salts, undergoes an extensive self-assembly process which eventually leads to the formati on of liquid crystalline cholesteric and hexagonal mesophases. In the isotropic phase, the presence of cylindrical aggregates is detected by small-angle X-ray scattering (SAXS). Their length and stability depen d on the ions present. Circular dichroism (CD) spectroscopy allows the detection and identification of two types of molecular aggregates. On e aggregate is likely to be formed by the assembling of discrete d(GpG ) tetramers, while the other by a continuous assembling of d(GpG) mole cules. The CD characteristics of the two aggregates are discussed in c onnection with those of the assembled species formed by deoxyoligonucl eotides with telomere-like sequences. The effect of added ions is disc ussed in detail.