Understanding SELEX: A Guide to Systematic Evolution of Ligands

In summary, SELEX (systematic evolution of ligands by exponential enrichment) is a technique used to identify DNA or RNA sequences that bind to a protein target with high affinity. It involves starting with a large pool of random sequences, binding them to a nucleic acid binding protein, and amplifying the sequences that bind the best through multiple selection cycles. This process results in a pool of highly "fit" sequences that bind to the target with the highest affinity. The original paper describing the SELEX method is by Turek and Gold (1990) and a classic paper applying the method to histone proteins can be found in the link provided.
  • #1
hivesaeed4
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Could someone explain SELEX (systematic evolution of ligands by exponential enrichment) or at least direct me to a good resource online because so far I have'nt found a decent explanation or website regarding SELEX online.
 
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  • #2
Don't bother. I've found something which will help me.
 
  • #3
SELEX is a technique to identify DNA or RNA sequences that bind to a protein target with high affinity. The method uses principles from evolution to accomplish this goal. You start out with a large pool of random DNA or RNA sequences. You then mix these sequences with your nucleic acid binding protein (NBP) in order to isolate the sequences that bind to the NBP the best. Next, you amplify the sequences isolated from the binding step then repeat the procedure by binding these sequences to your NBP again.

As you perform more and more cycles of selection, the DNA or RNA sequences that bind to the NBP get amplified while the sequences that do not bind the NBP do not get amplified. Soon, the pool of sequences consists of only the most "fit" sequences that bind to the NBP with the highest affinity.

Here's the citation for the original paper describing the SELEX method:
Turek and Gold, 1990. Systematic Evolution of Ligands by Exponential Enrichment: RNA Ligands to Bacteriophage T4 DNA Polymerase. Science, 249: 505. http://dx.doi.org/10.1126/science.2200121[/url .

Here's a link to a classic paper applying the SELEX method to find sequences that bind strongly to histone proteins. Figure 1 shows a nice graphical overview of the method:
http://groups.molbiosci.northwestern.edu/widomweb/pdfpapers/New%20DNA%20Sequence%20Rules%20for%20High.pdf
 
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What is SELEX?

SELEX stands for Systematic Evolution of Ligands by Exponential Enrichment. It is a laboratory technique used to identify and isolate specific RNA or DNA sequences that bind to a particular target molecule.

How does SELEX work?

SELEX involves multiple rounds of selection and amplification. In the first round, a large pool of random RNA or DNA sequences is exposed to the target molecule. The sequences that bind to the target are then separated and amplified through techniques such as PCR. This process is repeated for several rounds until the desired sequences are enriched and isolated.

What is the purpose of SELEX?

The purpose of SELEX is to identify and isolate specific RNA or DNA sequences that have high affinity and specificity for a particular target molecule. These sequences, called aptamers, can then be used for various applications such as diagnostics, therapeutics, and biosensors.

What are the advantages of SELEX?

SELEX offers several advantages over other methods of identifying specific target-binding molecules. It is highly specific, as the sequences are chosen based on their ability to bind to the target molecule. It is also highly customizable, as the target molecule can be chosen based on the desired application. Additionally, SELEX is a relatively fast and cost-effective technique.

What are some potential limitations of SELEX?

One limitation of SELEX is that it can only identify target-binding sequences that are present in the initial pool of random sequences. If the desired sequence is not present, SELEX will not be able to identify it. Additionally, SELEX can be affected by target impurities or structural changes, which may result in the selection of non-specific sequences. Therefore, careful optimization and validation are necessary to ensure the accuracy and reliability of SELEX results.

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