Enhance the sensitivity of your cellular and structural studies with expert-designed fluorescent-labeled peptides. Our state-of-the-art peptide synthesis conjugation technology allows for the precise incorporation of fluorescent dyes into your peptides at any desired position, providing site-specific labeling for maximum assay sensitivity. Expedite your projects today.

When to use fluorescent-labeled peptides in your project

Fluorescent-labeled peptides are produced by directly incorporating a fluorescent dye, such as FAM or FITC, into the peptide during the synthesis process. Labeling can also be carried out indirectly using biotinylated amino acids. Both methods allow for site-specific labeling, as the dye can be incorporated at any desired position, rather than distributed randomly throughout the molecule. Site-specific labeling offers two distinct advantages:

  • It allows researchers to study specific peptide regions or domains and understand how they interact with other molecules.
  • And it enables researchers to fine-tune the level of fluorescence signal, thus adapting assay sensitivity to their specific needs.

Advantages of using fluorescent-labeled peptides in your project

Fluorescent dyes are typically incorporated at the N-terminal, C-terminal, or at the side chain of a specific amino acid residue such as cysteine or lysine. These labels offer several advantages over other types of dyes. One of the main ones is that they can be easily visualized using fluorescence microscopy or other fluorescence-sensitive techniques. Their ability to emit light at a specific wavelength when activated by a light source of a different wavelength, makes them highly attuned and precise for detection.

Additionally, fluorescent labels are stable and generally non-toxic and, thus, ideal for monitoring biological processes in vitro and in vivo. Due to their well-characterized spectrum of emission and absorption, these dyes can also be multiplexed. In these cases, multiple dyes with non-overlapping spectra can be used in the same assay to label different structures or molecules within a sample, enabling the simultaneous analysis or localization of multiple targets. Due to their high signal-to-noise ratio, they are relatively easy to use and compatible with a wide range of experimental conditions.

A varied selection of fluorescent dyes can be used to label peptides:

Fluorescent Dye Derivative Absorption (nm) Emission (nm) Key features
Fluorescein FAM 495 516 High water solubility and high pH sensitive makes these dyes ideal for fluorescence microscopy, flow cytometry, and immunofluorescence-based assays
Fluorescein FITC 495 518 Commonly used in fluorescence resonance energy transfer (FRET) assays
Rhodamine TAMRA 552 578 Known for their stability and high fluorescence intensity, these dyes are commonly used in imaging, fluorescence microscopy, and others
Rhodamine SiR (silicon-rhodamine) dyes Wide range Wide range Known for their low toxicity and high cell permeability, these dyes ideal for imaging, localization, and in vivo applications
Cyanine Cy3 550 570 Brighter and more stable than fluorescein derivates, due to their high molar extinction coefficient, theses dyes are easily detected by naked eye on electrophoresis gels, and in solution
Cyanine Cy5 650 670 Brighter and more stable than fluorescein derivates, due to their high molar extinction coefficient, theses dyes are easily detected by naked eye on electrophoresis gels, and in solution
Coumarins, rhodamines, carbopyronins, and oxazines ATTO dyes Wide range Wide range Photostable with high rigidity and resistance to ozone degradation, making them ideal for microarray and other highly sensitive applications
Coumarin, rhodamine, cyanine, and xanthene family dyes Alexa Fluor dyes Wide range Wide range Typically used to dye cell structures or tissues in fluorescence microscopy assays

In addition to being conjugated to dyes, peptides can also be modified with intrinsically fluorescent amino acid residues such as tryptophan or tyrosine. However, their spectroscopic properties are complex, making it challenging to standardize and useful only for very precise experiments. The selection of fluorescent dye will be based on the specific application and properties of the label, including its excitation and emission spectra, stability, brightness, and sensitivity to pH.

Not sure where to begin? Contact our peptide synthesis experts to receive a proposal tailored to your experimental setting, budget, and requirements:

Common applications of fluorescent-labeled peptides

Fluorescent peptide probes versatile tools serving multiple applications:

  • Imaging
  • Intracellular localization studies
  • Protein interaction studies
  • Development of novel disease models
  • Biosensing

The most significant advantage of fluorescent peptides over other biomolecules such as antibodies is their superior ability to penetrate cell membranes. This property is invaluable for imaging and intracellular localization studies, particularly those involving protein interaction and cellular trafficking, crucial for understanding the underlying causes of diseases, and for the development of new therapeutics.

Although not as widespread, fluorescent peptides are increasingly used as inexpensive and practical probes for biosensing. These tools have been employed in a wide variety of experiments, ranging from the detection and measurement of nanoparticles, environmental monitoring, and clinical analysis and diagnosis.

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