Fluorescein Peptide Modifications – Dyes and Quenchers
AMC (7-Amino-4-methyl-coumarin)
UV-excitable dye, used in enzyme assays using cuvettes or flow cytometry.
| Dye | Excitation maximum | Emission maximum | Molar Extinction Coefficient |
|---|---|---|---|
| AMC | 353 nm | 422 nm | 19.000 |
Cy3, Cy5
Cy3, Cy5 are dyes with extremely high extinction coefficients and fluorescence. Thus, they are especially suitable for very sensitive localization assays of peptides in cells. Their disadvantage is the high instability of the molecules under peptide synthesis conditions. Therefore the yields are comparatively low.
| Dye | Excitation maximum | Emission maximum | Molar Extinction Coefficient |
|---|---|---|---|
| Cy™3 | 550 nm | 570 nm | 150.000 |
| Cy™5 | 650 nm | 670 nm | 250.000 |
Dabcyl
Dabcyl is a non-fluorescent dye predominantly used as a quencher for other fluorophores (esp. Fluorescein type dyes, EDANS.). If Dabcyl is coupled to a peptide in close proximity to a fluorophore, it absorbs the emitted light of the fluorophore. Enlarging this distance (i.e. by enzymatic cleavage of the peptide) results in excitation of the fluorophore with an emission signal that can be detected.
| Dye | Excitation maximum | Emission maximum | Molar Extinction Coefficient |
|---|---|---|---|
| Dabcyl | 453 nm | none | 32.000 |
Dansyl
Dansyl is also used as a fluorophore quencher. Unlike Dabcyl, it inherits own fluorescence and thus might not be as useful for highly sensitive assays.
| Dye | Excitation maximum | Emission maximum | Molar Extinction Coefficient |
|---|---|---|---|
| Dansyl | 335 nm | 526 nm | 4.600 |
2,4-Dinitrophenyl (DNP)
2,4-Dinitropheny is a non-fluorescent dye that can be used as a fluorophore quencher (see Dabcyl for more details).
| Dye | Excitation maximum | Emission maximum | Molar Extinction Coefficient |
|---|---|---|---|
| DNP | 348 nm | none | 18.000 |
DNP-Lysine
DNP-Lysineis a non-fluorescent dye that can be used as a fluorophore quencher, for custom peptide (see Dabcyl for more details).
| Dye | Excitation maximum | Emission maximum | Molar Extinction Coefficient |
|---|---|---|---|
| DNP-Lysine | 348 nm | none | 18.000 |
EDANS (5-((2-aminoethyl)amino)napthalene-1-sulfonic acid)
EDANS is a commonly used dye in FRET (fluorescence resonance energy transfer) peptides in combination with Dabcyl as quencher.
| Dye | Excitation maximum | Emission maximum | Molar Extinction Coefficient |
|---|---|---|---|
| EDANS | 335 nm | 493 nm | 5.900 |
Fluorescein
Fluorescein is the commonly used fluorescent dye in confocal laser-scanning microscopy and flow cytometry applications.
| Dye | Excitation maximum | Emission maximum | Molar Extinction Coefficient |
|---|---|---|---|
| Fluorescein | 495 nm | 520 nm | 83.000 |
NBD (7-nitrobenz-2-oxa-1, 3-diazole)
NBD is a fluorescent dye, used for amine modification.
| Dye | Excitation maximum | Emission maximum | Molar Extinction Coefficient |
|---|---|---|---|
| NBD | 486 nm | 543 nm | 27.000 |
p-Nitro-Aniline
p-Nitro-Aniline is a chromogen used as colorimetric enzyme substrate in many standard enzyme assays in cuvettes.
Rhodamine B
Rhodamine B represents one among a numerous range of rhodamine dyes, used in fluorescent peptide assays.
| Dye | Excitation maximum | Emission maximum | Molar Extinction Coefficient |
|---|---|---|---|
| Rhodamine | 550 nm | 580 nm | 90.000 |
Tamra
Tamra is the most commonly used rhodamine dye in fluorescence assays.
| Dye | Excitation maximum | Emission maximum | Molar Extinction Coefficient |
|---|---|---|---|
| Tamra | 544 nm | 576 nm | 90.000 |
