What are aptamers?
An aptamer is a nucleic acid or peptide that can bind specifically to a particular molecule. Aptamers are broadly classified into nucleic acid (DNA/RNA) aptamers and peptide aptamers based on composition, and their function is determined by the three-dimensional structure formed by these oligomers.
Among aptamers, nucleic acid aptamers composed of DNA/RNA are positioned as nucleic acid drugs along with siRNA, miRNA, antisense, decoy, and CpG oligo. mRNA, which has attracted attention as a coronavirus vaccine, is another nucleic acid medicine.
Aptamer was named from the Latin word “aptus” meaning "to fit" and the suffix “-mer” of oligomer, and was named by the group of Szostak et al.
Characteristics of Aptamers
Nucleic acid aptamers have been reported to bind to various proteins such as growth factors, enzymes, receptors, and viral proteins, as well as metal ions and small molecules. Like antibodies, aptamers can bind to disease-causing factors and cell surfaces and inhibit their functions, and new aptamers are being actively created around the world.
Characteristics of aptamers include
- Diversity of binding targets
- High binding and specificity
- Low immunogenicity
- Chemically synthesized in a short time
These advantages, which are not found in antibodies, are expected to be applied in the fields of pharmaceuticals and diagnostics.
SELEX（Systematic Evolution of Ligands by EXponential enrichment）
Nucleic acid aptamers are created by in vitro selection or SELEX.
First, DNA molecules that bind to the target protein are selected from a random DNA library. Then, DNA molecules that bind strongly to the target protein are isolated by PCR amplification of the sequences of those DNA molecules and repeated selection.
The DNA molecules thus obtained become the prototype aptamer. TAGCyx truncates these candidate molecules to the minimum necessary sequence and adds a mini hairpin structure at the end to stabilize the structure.