Amino Acids, Peptides, and ProteinsAmino AcidsAmino Acid SequenceSulfurAnhydridesMolecular Sequence DataSequence Homology, Amino AcidProteinsSulfur CompoundsAmino Acid SubstitutionAmino Acids, SulfurCloning, MolecularAmino Acids, EssentialAmino Acid Transport SystemsSequence AlignmentSulfur IsotopesSulfur DioxideBase SequenceAmino Acid MotifsEscherichia coliMutationBinding SitesMutagenesis, Site-DirectedDNA, ComplementaryKineticsSequence Homology, Nucleic AcidAmino Acids, Aromatic