Systematic evolution of ligands by exponential enrichment: Solution SELEX
First Claim
1. A method for identifying nucleic acid ligands from a candidate mixture of nucleic acids, said nucleic acid ligands being a ligand of a given target molecule comprising:
- a) contacting said candidate mixture with the target molecule, wherein nucleic acids having increased affinity to the target molecule form nucleic acid-target complexes;
b) partitioning the increased affinity nucleic acids from the remainder of the candidate mixture, said partitioning step resulting in two differentiable nucleic acid pools said nucleic acids in each pool having different relative affinities to said target molecule; and
c) amplifying the increased affinity nucleic acids to yield a ligand-enriched mixture of nucleic acids, whereby nucleic acid ligands of the target molecule may be identified.
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Abstract
Described herein are methods for improved partitioning between high and low affinity nucleic acid ligands identified through the SELEX method, termed solution SELEX. The solution SELEX method achieves partitioning between high and low affinity nucleic acid-target complexes through a number of methods, including (1) primer extension inhibition which results in differentiable cDNA products. Primer extension inhibition is achieved with the use of nucleic acid polymerases, including DNA or RNA polymerases, reverse transcriptase, and Qβ-replicase; (2) exonuclease hydrolysis inhibition which results in only the highest affinity ligands amplifying during PCR. This is achieved with the use of any 3'"'"'→5'"'"' double-stranded exonuclease; (3) linear to circle formation to generate molecules amplifiable during PCR; or (4) PCR amplification of single-stranded nucleic acids. A central theme of the method of the present invention is that the nucleic acid candidate mixture is screened in solution and results in preferential amplification of the highest affinity RNA ligand or catalytic RNA.
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Citations
10 Claims
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1. A method for identifying nucleic acid ligands from a candidate mixture of nucleic acids, said nucleic acid ligands being a ligand of a given target molecule comprising:
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a) contacting said candidate mixture with the target molecule, wherein nucleic acids having increased affinity to the target molecule form nucleic acid-target complexes; b) partitioning the increased affinity nucleic acids from the remainder of the candidate mixture, said partitioning step resulting in two differentiable nucleic acid pools said nucleic acids in each pool having different relative affinities to said target molecule; and c) amplifying the increased affinity nucleic acids to yield a ligand-enriched mixture of nucleic acids, whereby nucleic acid ligands of the target molecule may be identified. - View Dependent Claims (2, 3, 4, 5, 6, 7, 10)
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8. A method for identifying nucleic acid ligands from a candidate mixture of nucleic acids, said nucleic acid ligands being a ligand of a given target molecule comprising:
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a) contacting said candidate mixture with the given target molecule, wherein nucleic acids having an increased affinity to the target molecule form nucleic acid-target complexes; b) partitioning the increased affinity nucleic acids from the remainder of the candidate mixture, said partitioning step comprising; (i) performing a first primer extension with a nucleic acid polymerase in the presence of nucleotides sensitive to chemical cleavage; (ii) removing the target molecule; (iii) performing a second primer extension with a nucleic acid polymerase in the presence of modified nucleotides resistant to chemical cleavage; (iv) incubating said first and second primer extension products with a nucleotide cleaving chemical, whereby the extension product of the first primer extension is cleaved; and c) amplifying the increased affinity nucleic acids to yield a ligand-enriched mixture of nucleic acids, whereby nucleic acid ligands of the given target molecule may be identified.
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9. A method for identifying double-stranded nucleic acid ligands from a candidate mixture of nucleic acids, said double-stranded nucleic acid ligands being a ligand of a given target molecule comprising:
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a) contacting said candidate mixture with the given target molecule, wherein nucleic acids having an increased affinity to the target molecule form nucleic acid-target complexes; b) partitioning the increased affinity nucleic acids from the remainder of the candidate mixture, said partitioning step comprising; (i) incubating the increased affinity nucleic acids with exonuclease wherein full length double-stranded nucleic acids not forming nucleic acid-target complexes are degraded and the double-stranded nucleic acids forming nucleic acid-target complexes are partially protected from degradation; (ii) removing said exonuclease and said target; (iii) primer extending said double-stranded nucleic acids with polymerase, wherein the double-stranded nucleic acid ligand-enriched candidate mixture is regenerated from the partially protected nucleic acids; and c) amplifying the primer extended double-stranded nucleic acids to yield a ligand-enriched mixture of double-stranded nucleic acids, whereby the double-stranded nucleic acid ligands of the given target molecule may be identified.
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Specification