Can Bio-Synthesis prepare dual-labeled peptides?
Yes. Dual labels can be introduced through protected building blocks, orthogonal side-chain chemistry, post-synthetic conjugation, or a hybrid route.
Can FRET peptides include dark quenchers?
Yes. Dark quenchers such as DABCYL and related systems are often used in enzyme substrates because they suppress donor fluorescence without generating a strong acceptor-emission channel.
What purity is recommended?
High purity is generally preferred because unlabeled, singly labeled, truncated, or free-dye species can affect fluorescence background and assay interpretation.
What is a FRET peptide?
A FRET peptide contains a donor fluorophore and an acceptor fluorophore or quencher positioned so that a molecular event changes energy transfer and fluorescence output.
How does a quenched FRET substrate work?
When donor and quencher are close, donor fluorescence is suppressed. Enzymatic cleavage separates the labels and increases donor fluorescence.
How far apart should the labels be?
FRET is typically sensitive over nanometer-scale distances. The optimal separation is pair- and architecture-dependent and must account for linkers, orientation, sequence conformation, and the assay environment.
Which donor–acceptor pairs are commonly used?
Common systems include EDANS–DABCYL, FAM–DABCYL, FAM–TAMRA, Cy3–Cy5, and Alexa Fluor 488–Alexa Fluor 594. The best pair depends on the instrument and assay.
How are FRET peptides characterized?
Identity and chemical purity are commonly evaluated by LC-MS and analytical HPLC or UPLC. Fluorescence behavior, free-dye removal, and assay performance should be evaluated separately when required.
Can other modifications be added?
Often yes. FRET peptides may include affinity tags, isotope labels, cyclization, PEG spacers, or targeting motifs when chemistry and purification are compatible.
How should FRET peptides be stored?
Store protected from light, minimize repeated freeze–thaw cycles, and follow formulation-specific guidance. Some dyes and constructs benefit from low-temperature, low-oxygen, or dry storage.