Structure-based design of a fluorimetric redox active peptide probe

Structure-based iterative design was used to prepare a disulfide-containing nonapeptide as a fluorimetric probe for chemical and biochemical disulfide forming and breaking reactions. The peptide is composed entirely of natural amino acids and exhibits a marked (42%) change in fluorescence between its oxidized and its reduced states. The probe is easily synthesized and highly water soluble and exhibits well-behaved kinetics on reduction with the reductant tris–carboxyethylphosphine. The reduced peptide is an excellent substrate of the enzyme quiescin–sulfhydryl oxidase and may find utility in the characterization of other disulfide oxidoreductases.