High-affinity nucleic acid ligands that discriminate between theophylline and caffeine

摘要

Methods are described for the identification and preparation of nucleic acid ligand ligands to theophylline and caffeine. Included in the invention is a method for identifying nucleic acid ligands with high affinity and selectivity for a target molecule, termed counter-SELEX. One embodiment of counter-SELEX is comprised of the steps of a) preparing a candidate mixture of nucleic acids; b) contacting the candidate mixture with the target, wherein nucleic acids having an increased affinity to the target relative to the candidate mixture may be partitioned form the remainder of the candidate mixture; partitioning the increased affinity nucleic acids from the remainder of the candidate mixture; d) contacting the increased affinity nucleic acids with one or more non-target molecules such that nucleic acid ligands to the non-target molecule(s) are removed; and e) amplifying the nucleic acids with specific affinity to the target molecule to yield a mixture of nucleic acids enriched for nucleic acid sequences with a relatively higher affinity and specificity for binding to the target molecule. Included in the invention are specific nucleic acid ligands to theophylline identified by the method of counter-SELEX.