Small-angle scattering applications to the analysis of aptamer structure and conformational changes

Aptamers, structured single-chain oligonucleotides, are promising tools for detection of a wide variety of compounds, from high to low molecular weight, and affecting on them. The aptamers that are most affine for a detectable compound are selected from the libraries of random sequences by the SELEX method (Systematic evolution of ligands by exponential enrichment). The reason why aptamers deserve a special consideration lies in the specific features of their structure and the mechanism of binding to their target. Aptamers can be exploited for metal-ion sensing, biosensing, drug delivery and other functions. To apply the oligonucleotides in the medicine, ecology, food production, agriculture, etc., we need to know how the aptamers bind to their targets, how they change their conformation upon specific binding and how the environment influences on the affinity of aptamers. Small-Angle X-ray scattering showed that the interaction of aptamers with heavy metal and other divalent ions proceeds according to different mechanisms, and the aptamers used undergo different conformational changes.