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`What is an Aptamer? – Aptamers and SELEX
`
`What is an
`Aptamer?
`The term “Aptamer”
`was coined by Andy
`Ellington. It stems
`from the Latin terms
`“aptus,” meaning to
`fit, and
`
`Structure of aptamer developed by Base Pair
`Biotechnologies to IL-7
`“meros,” meaning part. Aptamers are short, single-stranded DNA or
`RNA (ssDNA or ssRNA) molecules that can selectively bind to a
`specific target, including proteins, peptides, carbohydrates, small
`molecules, toxins, and even live cells. Aptamers assume a variety of
`shapes due to their tendency to form helices and single-stranded loops.
`They are extremely versatile and bind targets with high selectivity and
`specificity. Rather than primary sequence, aptamer binding is
`determined by its tertiary structure. Target recognition and binding
`involve three dimensional, shape-dependent interactions as well
`as hydrophobic interactions, base-stacking, and intercalation.
`Aptamers bind because they “fit” their targets.
`
`ViewBase Pair Webinars:
`
`• Aptamer Applications in Research, Diagnostics and Therapeutics
`
`https://www.basepairbio.com/what-is-an-aptamer/[12/30/2021 5:09:02 PM]
`
`Exhibit 2157
`Page 01 of 07
`
`
`
`Whatis an Aptamer? - Aptamers and SELEX - Base Pair Biotechnologies
`
`¢ Aptamer-Based Biosensors
`
`VIEW BASE PAIR WEBINARS
`
`SELEX AptamerSelection
`Aptamers with affinity for a desired target are selected from a large oligonucleotide library through a process
`called SELEX,which stands for Sequential Evolution of Ligands by Exponential Enrichment. Through an
`iterative process, non-binding aptamers are discarded and aptamers binding to the proposedtarget are
`
`expanded.Initial positive selection rounds are sometimes followed by negative selection. This improves the
`selectivity of the resulting aptamer candidates. Multiple rounds of SELEX are performed with increasing
`
`stringency to enhance enrichmentof the oligonucleotide pool. Base Pair maintains several proprietary
`oligonucleotide libraries for use in aptamer selection. Base Pairhas also patented a multiplex format of
`
`SELEX. Learn more about multiplex SELEX.
`
`SELEXStep 1. Bindoligonucleotide library and discard non-binders
`
`Add ssRNA
`or ssDNA
`Library ———~p»
`
`Affinity
`Column
`with
`Target
`Molecule
`
`Discard
`Non-Binders
`
`Saf
`
`SELEX Step 2. Elute oligonucleotides that bind desired target
`
`Exhibit 2157
`
`.
`Page 02 of O7
`https://www.basepairbio.com/what-is-an-aptamer/[12/30/2021 5:09:02 PM]
`
`Exhibit 2157
`Page 02 of 07
`
`
`
`What is an Aptamer? - Aptamers and SELEX - Base Pair Biotechnologies
`
`SELEX Step 3. Perform PCR to amplify eluted binders
`
`https://www.basepairbio.com/what-is-an-aptamer/[12/30/2021 5:09:02 PM]
`
`Exhibit 2157
`Page 03 of 07
`
`
`
`What is an Aptamer? - Aptamers and SELEX - Base Pair Biotechnologies
`
`SELEX Step 4. Repeat steps 1 through 3 using enriched oligonucleotide pool
`
`https://www.basepairbio.com/what-is-an-aptamer/[12/30/2021 5:09:02 PM]
`
`Exhibit 2157
`Page 04 of 07
`
`
`
`What is an Aptamer? - Aptamers and SELEX - Base Pair Biotechnologies
`
`Completion of SELEX Multiple rounds of SELEX (often 6 to
`12) are typically performed. More challenging applications may require
`additional rounds. Alternate selection methods may be completed in
`fewer rounds. Selection design will vary based on the target of interest
`and end-use application.
`
`Selection of Final Aptamer Sequences The SELEX process
`yields ~106 aptamer sequences. Identifying the best candidates is a
`specialized process employing a variety of analytical techniques at Base
`Pair. See the Custom Aptamer Discovery page for more information on
`aptamer characterization, optimization, and application.
`
`Project-Specific SELEX Questions Base Pair aptamer
`
`https://www.basepairbio.com/what-is-an-aptamer/[12/30/2021 5:09:02 PM]
`
`Exhibit 2157
`Page 05 of 07
`
`
`
`Whatis an Aptamer? - Aptamers and SELEX- Base Pair Biotechnologies
`
`specialists are available to answerproject-specific questions. Please feel
`
`free to
`
`1.
`
`Acknowledgements: The following programs were utilized to
`
`generate the IL-7 aptamerstructure:
`
`T. Macke and D.A. Case. Modeling unusual nucleic acid
`
`structures. In Molecular Modeling ofNucleic Acids, N.B. Leontes
`
`andJ. SantaLucia, Jr., eds. (Washington, DC: American Chemical
`
`Society, 1998), pp. 379-393.
`
`eek
`
`.
`
`The Aptamer Discovery Company
`
`,
`
`By
`
`Exhibit 2157
`Page 06 of 07
`https://www.basepairbio.com/what-is-an-aptamer/[12/30/2021 5:09:02 PM]
`
`Exhibit 2157
`Page 06 of 07
`
`
`
`What is an Aptamer? - Aptamers and SELEX - Base Pair Biotechnologies
`
`https://www.basepairbio.com/what-is-an-aptamer/[12/30/2021 5:09:02 PM]
`
`Exhibit 2157
`Page 07 of 07
`
`