Fluorescent peptides are used as probes in cell biology, protease assays and high-content screening. ChinaPeptides labels peptides with FITC, 5-FAM, TAMRA, Cy dyes and other research fluorophores.
FRET peptides can be designed with matched donor–acceptor pairs and cleavage sequences specified by the customer.
Dye choice is an assay decision: FITC is common and inexpensive; TAMRA and cyanine dyes shift the spectrum and can reduce overlap with cellular autofluorescence. A spacer such as Ahx or PEG often sits between the dye and the recognition sequence so that the fluorophore does not dominate binding.
Labeling is part of peptide modification chemistry and is planned with the synthesis, not painted on afterwards if the sequence is already insoluble.