Aptamers, NucleotideSELEX Aptamer TechniqueAptamers, PeptideAmino AcidsNucleotidesSequence Homology, Amino AcidAmino Acid SequenceMolecular Sequence DataBase SequenceCloning, MolecularAmino Acid SubstitutionNucleic Acid ConformationBinding SitesEscherichia coliSequence Homology, Nucleic AcidSequence AlignmentMutationDNARNAKineticsAmino Acids, EssentialProtein BindingPolymorphism, Single NucleotideSequence Analysis, DNAAdenine NucleotidesAmino Acid Transport SystemsModels, MolecularAmino Acid MotifsPhylogenyDNA, ComplementaryOligonucleotidesSubstrate SpecificityGuanine NucleotidesRecombinant ProteinsProtein ConformationDNA PrimersMutagenesis, Site-DirectedRestriction MappingProtein Structure, TertiaryGenes, BacterialGene LibraryRNA, MessengerCell LineBacterial ProteinsPlasmids