title: Characterization and application of a DNA aptamer binding to L-tryptophan.
abstract: DNA aptamers for specific recognition of L-tryptophan have been evolved by a SELEX (systematic evolution of ligands by exponential enrichment) technique. Truncation-mutation experiments suggest that a 34-mer sequence, Trp3a-1, possesses the strongest binding ability to L-tryptophan. Trp3a-1 is predicted to adopt a loop-stem secondary structure, in which the loop may further fold into a binding pocket for L-tryptophan with the help of the stem. The specificity investigation shows that Trp3a-1 strongly binds to L-tryptophan, has almost no binding to other amino acids, and weakly binds to some tryptophan analogs and peptides containing the L-tryptophan residue. The binding of Trp3a-1 to L-tryptophan is mainly contributed to by hydrogen bonds and precise stacking formed between the binding pocket of Trp3a-1 and all groups on L-tryptophan. This aptamer has also been proved to be an effective ligand for the chiral separation of D/L-tryptophan. L-tryptophan and its derivatives are known to play important biological roles; this aptamer ligand could be used as a tool for the analysis of tryptophan and other related studies.
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Xiaojuan
authors.initials: X
authors.lastname: Yang
authors.forename: Tao
authors.initials: T
authors.lastname: Bing
authors.forename: Hongcheng
authors.initials: H
authors.lastname: Mei
authors.forename: Canliang
authors.initials: C
authors.lastname: Fang
authors.forename: Zehui
authors.initials: Z
authors.lastname: Cao
authors.forename: Dihua
authors.initials: D
authors.lastname: Shangguan
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry*; D001483:Base Sequence; D001665:Binding Sites; D001667:Binding, Competitive; D015374:Biosensing Techniques / Q000379:methods*; D006860:Hydrogen Bonding; D008024:Ligands; D058977:Molecular Sequence Annotation; D014364:Tryptophan / Q000032:analysis* / Q000737:chemistry
chemical_list: D052157:Aptamers, Nucleotide; D008024:Ligands; D014364:Tryptophan