Dear Swan,

Thank you for your questions regarding aptamer conformation. Aptamer conformation is not straightforward, as a given sequence can take on multiple conformations. While some aptamers maintain one primary conformation, others do not. The secondary structure can depend on the actual sequence of the apatmer as well as external factors, including the pH and composition of the dilution buffer. In regards to whether aptamers can behave differently due to batch to batch variations, one can imagine a scenario where purity may influence structure and function. However, in general the synthesis should not affect aptamer conformation. Interestingly, we too were not able to easily find any online literature that specifically documents this phenomenon, though The Aptamer Handbook, edited by Sven Klussman presents a lot of useful information on aptamer activity, selection and design.

Please let me know if I can help you further.

Regards,
Brea

Dear Parisa,

Thank you for your question regarding SELEX design. In his 2009 paper titled Design, Synthesis, and Amplification of DNA Pools for In Vitro Selection, Dr. Andrew Ellington suggests using primers of approximately 20 nucleotides due to their melting temperature. To avoid secondary structure formation, he suggests using MIT’s web based program PRIMER3. Please let me know if you have further questions.

Best regards,
Elizabeth

Dear Eyal,
Thank you for your interest in TriLink’s Aptamer Libraries. The complexity of the final library varies with the random region length. Libraries with longer random regions have more unique sequence motifs than libraries with shorter random regions. However, not all possible unique sequences can be represented in each selection. In contrast, libraries with shorter random regions will give you a better representation of all possible sequences but are inherently less complex than a library with a longer randomer region. However, once an aptamer is selected shorter aptamers are easier and less expensive to synthesize

Aptamers have been designed to bind to specific amino acids.Geiger et. al. found an aptamer that distinguished with a 12,000-fold improvement between L-arginine and D-arginine. I don’t know the specific discrimination between Proline and Glycine. It would need to be determined experimentally. Proline and Glycine have different structures but the location within the protein and the protein folding may affect the ability to find an appropriate aptamer.

Good luck with your experiments.

Best regards,
Sabrina Shore, MS