Further nuclease stabilization is achieved by substitution of 2?-OCH₃ for 2?-OH at purine positions. As the 2?-OCH₃ moiety is not compatible with current SELEX process enzymes, this alteration must occur during chemical synthesis following evolution of a specific aptamer sequence. Generally, most of the 2?-OH purines can be substituted without loss of binding activity. At some locations, purines cannot be substituted without loss of affinity. In addition to protection against endonucleases, it is useful to protect against 3? exonuclease activity. Therefore the 3? nucleotide is inverted to form a new 5?-OH, with a 3?-3? linkage to the penultimate base. Finally, synthesis incorporates nucleophilic amines or thiols, lending flexibility for attachment of the escorted species or other desirable modifications.

step 1 c. It is a bulk-reduced oligonucleotide you to definitely exits this new SELEX techniques which can be truncated, then protected against nucleases, and you may conjugated to the cargo. For for the vivo imaging, we typically pair a great radiometal chelator towards the 5? Continue reading “Final steps in escort aptamer thinking include man-made changes of the truncated aptamer”