Classic Peptide Labeling Dyes
AAT Bioquest offers classic peptide labeling dyes in a variety of chemical reactivities, as well as conjugated to peptide substrates for enzyme activity assays. Choose from our comprehensive portfolio of:
- Coumarin and coumarin derivatives
- Fluorescein dyes
- Rhodamine dyes
- Cyanine dyes
FRET Donor/Acceptor Dyes
In addition to Tide Fluor™ and Tide Quencher™ FRET pairs, we offer various combinations of classic donor and acceptor dyes. Develop FRET peptides for measuring enzyme activity, receptor-ligand interactions, colocalization studies and much more.
Peptide Labeling Strategies
Labeled peptides can prepared by either modifying isolated peptides or by incorporating the label during solid-phase synthesis. Common strategies for labeling peptides with fluorophores include:
- Labeling during peptide synthesis – dyes that can withstand unblocking procedures can be incorporated onto the amino terminus of the peptide chain.
- N-terminal modification: N-terminus refers to the free amine group (-NH2) at the start of a protein or polypeptide chain. It can be modified co- or post-translationally using amine-reactive succinimidyl ester fluorophores.
- Lysine residues: the ε-amino group of lysine residues can be modified using amine-reactive succinimidyl ester fluorophores.
- C-terminal modification: C-terminus refers to the carboxyl group (-COOH) at the end of a protein or polypeptide chain. It can be modified post-translationally typically after C-terminal amidation.
- Synthetic peptides can be covalently labeled by thiol-reactive protein labels. Thiol-reactive protein labels may be used if a cysteine is available on the peptide chain.
- Unnatural amino acids could be incorporated in peptide chains during synthesis, and then labeled with dyes or other probes through bioorthogonal reactions, for example, azide and alkynes based reactions, and ketone-aldehyde reaction.