The use of supramolecular structures as protein ligands

Congo red dye as well as other eagerly self-assembling organic molecules which form rod-like or ribbon-like supramolecular structures in water solutions, appears to represent a new class of protein ligands with possible wide-ranging medical applications. Such molecules associate with proteins as integral clusters and preferentially penetrate into areas of low molecular stability. Abnormal, partly unfolded proteins are the main binding target for such ligands, while well packed molecules are generally inaccessible. Of particular interest is the observation that local susceptibility for binding supramolecular ligands may be promoted in some proteins as a consequence of function-derived structural changes, and that such complexation may alter the activity profile of target proteins. Examples are presented in this paper

NMR Characterization of the Aggregation State of the Azo Dye Sunset Yellow in the Isotropic Phase

The azo dye sunset yellow is known to form lyotropic liquid crystals as a function of both temperature and sample composition. Numerous studies have been performed to investigate the aggregation processes in these liquid crystals; however, less attention has been paid to the nature of the aggregates in the isotropic phase. In this study we employ diffusion nuclear magnetic resonance methods to investigate the hydrodynamic properties of sunset yellow aggregates at a range of concentrations in isotropic solution. The results of these experiments are interpreted in terms of a simple thermodynamic model for aggregation and suggest that the aggregates are comprised of tens to hundreds of monomer units at the concentrations investigated. The results also demonstrate that the average number of molecules per aggregate is a factor of approximately 5 larger than previously reported