iFluor® 570 succinimidyl ester
AAT Bioquest's iFluor® dyes are optimized for labeling proteins, in particular, antibodies. These dyes are bright, photostable and have minimal quenching on proteins. They can be well excited by the major laser lines of fluorescence instruments (e.g., 350, 405, 488, 555 and 633 nm). iFluor® 570 family has the spectral properties essentially identical to those of Cy3B. It is a superior replacement to Cy3B with greatly improved water solubility compared to Cy3B that is barely soluble in aqueous solutions. It maintains other charactuers of Cy3B, e.g., high fluorescence quantum yield with greatly enhanced photostability. iFluor® 570 family has fluorescence that is pH-independent from pH 3 to 11. iFluor® 570 SE is reasonably stable and shows good reactivity and selectivity with protein amino groups.
Example protocol
PREPARATION OF STOCK SOLUTIONS
Unless otherwise noted, all unused stock solutions should be divided into single-use aliquots and stored at -20 °C after preparation. Avoid repeated freeze-thaw cycles.
1. Protein stock solution (Solution A)
Mix 100 µL of a reaction buffer (e.g., 1 M sodium carbonate solution or 1 M phosphate buffer with pH ~9.0) with 900 µL of the target protein solution (e.g. antibody, protein concentration >2 mg/mL if possible) to give 1 mL protein labeling stock solution. Note: The pH of the protein solution (Solution A) should be 8.5 ± 0.5. If the pH of the protein solution is lower than 8.0, adjust the pH to the range of 8.0-9.0 using 1 M sodium bicarbonate solution or 1 M pH 9.0 phosphate buffer. Note: The protein should be dissolved in 1X phosphate buffered saline (PBS), pH 7.2-7.4. If the protein is dissolved in Tris or glycine buffer, it must be dialyzed against 1X PBS, pH 7.2-7.4, to remove free amines or ammonium salts (such as ammonium sulfate and ammonium acetate) that are widely used for protein precipitation. Note: Impure antibodies or antibodies stabilized with bovine serum albumin (BSA) or gelatin will not be labeled well. The presence of sodium azide or thimerosal might also interfere with the conjugation reaction. Sodium azide or thimerosal can be removed by dialysis or spin column for optimal labeling results. Note: The conjugation efficiency is significantly reduced if the protein concentration is less than 2 mg/mL. For optimal labeling efficiency the final protein concentration range of 2-10 mg/mL is recommended.2. iFluor™ 570 SE stock solution (Solution B)
Add anhydrous DMSO into the vial of iFluor™ 570 SE to make a 10 mM stock solution. Mix well by pipetting or vortex. Note: Prepare the dye stock solution (Solution B) before starting the conjugation. Use promptly. Extended storage of the dye stock solution may reduce the dye activity. Solution B can be stored in freezer for two weeks when kept from light and moisture. Avoid freeze-thaw cycles.SAMPLE EXPERIMENTAL PROTOCOL
This labeling protocol was developed for the conjugate of Goat anti-mouse IgG with iFluor™ 570 SE. You might need further optimization for your particular proteins. Note: Each protein requires distinct dye/protein ratio, which also depends on the properties of dyes. Over labeling of a protein could detrimentally affects its binding affinity while the protein conjugates of low dye/protein ratio gives reduced sensitivity.
Run conjugation reaction
- Use 10:1 molar ratio of Solution B (dye)/Solution A (protein) as the starting point: Add 5 µL of the dye stock solution (Solution B, assuming the dye stock solution is 10 mM) into the vial of the protein solution (95 µL of Solution A) with effective shaking. The concentration of the protein is ~0.05 mM assuming the protein concentration is 10 mg/mL and the molecular weight of the protein is ~200KD. Note: We recommend to use 10:1 molar ratio of Solution B (dye)/Solution A (protein). If it is too less or too high, determine the optimal dye/protein ratio at 5:1, 15:1 and 20:1 respectively.
- Continue to rotate or shake the reaction mixture at room temperature for 30-60 minutes.
Purify the conjugation
The following protocol is an example of dye-protein conjugate purification by using a Sephadex G-25 column.- Prepare Sephadex G-25 column according to the manufacture instruction.
- Load the reaction mixture (From "Run conjugation reaction") to the top of the Sephadex G-25 column.
- Add PBS (pH 7.2-7.4) as soon as the sample runs just below the top resin surface.
- Add more PBS (pH 7.2-7.4) to the desired sample to complete the column purification. Combine the fractions that contain the desired dye-protein conjugate. Note: For immediate use, the dye-protein conjugate need be diluted with staining buffer, and aliquoted for multiple uses. Note: For longer term storage, dye-protein conjugate solution need be concentrated or freeze dried.
Spectrum
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Product family
Name | Excitation (nm) | Emission (nm) | Extinction coefficient (cm -1 M -1) | Quantum yield | Correction Factor (260 nm) | Correction Factor (280 nm) |
iFluor® 350 succinimidyl ester | 345 | 450 | 200001 | 0.951 | 0.83 | 0.23 |
iFluor® 405 succinimidyl ester | 403 | 427 | 370001 | 0.911 | 0.48 | 0.77 |
iFluor® 488 succinimidyl ester | 491 | 516 | 750001 | 0.91 | 0.21 | 0.11 |
iFluor® 514 succinimidyl ester | 511 | 527 | 750001 | 0.831 | 0.265 | 0.116 |
iFluor® 532 succinimidyl ester | 537 | 560 | 900001 | 0.681 | 0.26 | 0.16 |
iFluor® 555 succinimidyl ester | 557 | 570 | 1000001 | 0.641 | 0.23 | 0.14 |
iFluor® 594 succinimidyl ester | 587 | 603 | 2000001 | 0.531 | 0.05 | 0.04 |
iFluor® 633 succinimidyl ester | 640 | 654 | 2500001 | 0.291 | 0.062 | 0.044 |
iFluor® 647 succinimidyl ester | 656 | 670 | 2500001 | 0.251 | 0.03 | 0.03 |
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References
View all 37 references: Citation Explorer
Fluorescence Anisotropy-Based Assay for Characterization of Ligand Binding Dynamics to GPCRs: The Case of Cy3B-Labeled Ligands Binding to MC4 Receptors in Budded Baculoviruses.
Authors: Veiksina, Santa and Tahk, Maris-Johanna and Laasfeld, Tõnis and Link, Reet and Kopanchuk, Sergei and Rinken, Ago
Journal: Methods in molecular biology (Clifton, N.J.) (2021): 119-136
Authors: Veiksina, Santa and Tahk, Maris-Johanna and Laasfeld, Tõnis and Link, Reet and Kopanchuk, Sergei and Rinken, Ago
Journal: Methods in molecular biology (Clifton, N.J.) (2021): 119-136
Quantitative analysis of fluorescent ligand binding to dopamine D3 receptors using live-cell microscopy.
Authors: Allikalt, Anni and Laasfeld, Tõnis and Ilisson, Mihkel and Kopanchuk, Sergei and Rinken, Ago
Journal: The FEBS journal (2021): 1514-1532
Authors: Allikalt, Anni and Laasfeld, Tõnis and Ilisson, Mihkel and Kopanchuk, Sergei and Rinken, Ago
Journal: The FEBS journal (2021): 1514-1532
Fluorescent ligands for dopamine D2/D3 receptors.
Authors: Allikalt, Anni and Purkayastha, Nirupam and Flad, Khajidmaa and Schmidt, Maximilian F and Tabor, Alina and Gmeiner, Peter and Hübner, Harald and Weikert, Dorothee
Journal: Scientific reports (2020): 21842
Authors: Allikalt, Anni and Purkayastha, Nirupam and Flad, Khajidmaa and Schmidt, Maximilian F and Tabor, Alina and Gmeiner, Peter and Hübner, Harald and Weikert, Dorothee
Journal: Scientific reports (2020): 21842
Unifying Mechanism for Thiol-Induced Photoswitching and Photostability of Cyanine Dyes.
Authors: Gidi, Yasser and Payne, Liam and Glembockyte, Viktorija and Michie, Megan S and Schnermann, Martin J and Cosa, Gonzalo
Journal: Journal of the American Chemical Society (2020): 12681-12689
Authors: Gidi, Yasser and Payne, Liam and Glembockyte, Viktorija and Michie, Megan S and Schnermann, Martin J and Cosa, Gonzalo
Journal: Journal of the American Chemical Society (2020): 12681-12689
Fluorescence lifetime imaging with a single-photon SPAD array using long overlapping gates: an experimental and theoretical study.
Authors: Ardelean, Andrei and Ulku, Arin Can and Michalet, Xavier and Charbon, Edoardo and Bruschini, Claudio
Journal: Proceedings of SPIE--the International Society for Optical Engineering (2019)
Authors: Ardelean, Andrei and Ulku, Arin Can and Michalet, Xavier and Charbon, Edoardo and Bruschini, Claudio
Journal: Proceedings of SPIE--the International Society for Optical Engineering (2019)
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