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Fluorescent Thiol Protein Labeling

Maleimides of Fluorescent Dyes enable one-step labeling & detection of both proteins (e.g. antibodies) and any other Thiol-containing macromolecules.

In general, Thiol Labeling is more specific than Amine Labeling due to the relatively low abundance of cysteines compared to lysines. Since however, appearance of cysteines and lysines varies among different proteins, the amino acid sequence and tertiary structure of the protein of interest must be analyzed prior to deciding on the labeling strategy. The intended application of the fluorescent protein also determines the labeling strategy. Amine labeling is used for immunochemistry whereas Thiol labeling is preferred for investigating structure, function and protein interaction.

Maleimides of Alexa Fluor (AF) dyes are available as well.

Emission ColorProductsAbs max. [nm]Em max. [nm]Replacement for
blue-greenAtto 425 Protein Labeling Kit for thiol groups436484DEAC: 430 / 477 nm
greenAtto 488 Protein Labeling Kit for thiol groups501523Alexa Fluor 488: 495 / 519 nm
Fluorescein (FITC): 495 / 520 nm
FAM: 495 / 520 nm
Oregon Green 514: 506 / 526 nm
Rhodamine green: 503 / 528 nm
Rhodamine 123: 507 / 529 nm
yellow-
green
Atto 532 Protein Labeling Kit for thiol groups532553Alexa Fluor 532: 531 / 554 nm
Bodipy 530/550: 534 / 554 nm
yellowAtto 550 Protein Labeling Kit for thiol groups554576Alexa Fluor 555: 555 / 565 nm
Cy 3: 550 / 570 nm
Alexa Fluor 546: 556 / 573 nm
TAMRA: 546 / 576 nm
Rhodamine Red: 560 / 580 nm
Spectrum Orange: 559 / 588 nm
orangeTexas Red Protein Labeling Kit for thiol groups583603Rhodamine ITC: 572 / 596 nm
Cy 3.5: 581 / 596 nm
ROX: 576 / 601 nm
Alexa Fluor 568: 578 / 603 nm
orangeAtto 590 Protein Labeling Kit for thiol groups594624Alexa Fluor 594: 590 / 617 nm
Alexa Fluor 610: 612 / 628 nm
redAtto 647N Protein Labeling Kit for thiol groups644669Alexa Fluor 647: 650 / 665 nm
Cy 5: 643 / 667 nm
near-IRAtto 655 Protein Labeling Kit for thiol groups663684Alexa Fluor 660: 664 / 691 nm
Cy 5.5: 675 / 694 nm