Aptamers are single-stranded nucleic acids (both DNAs and RNAs) with a high affinity toward target molecules. A number of aptamers were selected to against a wide variety of target molecules, such as proteins and viruses. Aptamers are usually referred to as “chemical antibodies” because of their high selectivity and binding affinity toward target molecules. Compared to antibodies, aptamers possess the following merits. Firstly, the structures and sizes of aptamers are more flexible and smaller than those of antibodies. Thus, aptamers can recognize and bind to the targets which are inaccessible for antibodies, such as smaller targets or some hidden binding domains. Secondly, aptamers are much cheaper and require less time for production than antibodies since they could be massively synthesized. Last, aptamers are more stable under most conditions, which increases their shelf life. Aptamers are usually identified through an in vitro experimental approach firstly implemented in the 1990s named systematic evolution of ligands by exponential enrichment (SELEX). SELEX has the ability to select aptamers bounding to target molecules with high selectivity and binding affinity. However, the SELEX process is time consuming and characterization of the representative aptamer candidates from SELEX is rather laborious. Artificial intelligence (AI) could help to rapidly identify the potential aptamer candidates from a vast number of sequences. Here you have a classical example of an aptamer, illustrated by the NMR structure of a GTP aptamer (PDB code: 2AU4)

#molecularart ... #aptamer ... #gtp ... #chemicalantibody ... #binding ... #nmr

Structure rendered with @proteinimaging and depicted with @corelphotopaint