Fluorescence and Dye Labeling Peptides

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Need fluorescent or dye-labeled peptides for cell imaging or flow cytometry? Science-Peptide provides fluorescent and dye-labeled peptide synthesis service, FITC, FAM, TAMRA, Cy3/Cy5, biotin, rhodamine and other dyes are available for selection, fixed-point labeling, high purity, and strict quality control. Welcome to contact us.

Fluorescent and dye-labeled peptides: seeing is believing

Why labeled peptides?
Anyone who does biological research understands that often it is not enough to have a peptide, but you have to be able to "see" it - to see which cell it has entered, what proteins it has bound to, and where it has gone after it has traveled around the body.

Fluorescent and dye-labeled peptides do just that. By attaching a fluorescent group or dye to a peptide, the peptide has "eyes" and can be tracked wherever it goes.

What experiments can't be done without it?
Cellular imaging: to see if the peptide has entered the cell and where it is staying
Flow cytometry: analysis of the proportion of peptide-binding positive cells that
Fluorescence polarization: a study of peptide-receptor binding affinity
Tissue localization: looking at the distribution of peptides in animals
The FRET experiment: studying protein-protein interactions

What We Can Do

1. Type of Fluorescent Dye, Depending on What You Need

Dye type	Excitation/emission wavelengths	Common applications
FITC	495nm / 525nm	Flow, fluorescence microscope, cost-effective
FAM	495nm / 520nm	Similar to FITC, commonly used for DNA/peptide labeling
TAMRA	555nm / 580nm	FRET receptor, confocal imaging
Cy3	550nm / 570nm	Stable, high brightness, commonly used for tissue imaging
Cy5	650nm / 670nm	Far-red, low tissue background, suitable for in vivo imaging
Rhodamine B	540nm / 625nm	Mitochondrial labeling, light stable
Rhodamine Red	570nm / 590nm	Cellular imaging, resistant to photobleaching
Biotin	Non-luminous, affinity-based	ELISA, pull-down, histochemistry

Have other dye needs? Alexa Fluor series, Texas Red, Pacific Blue, you name it, we can do it.

2. Mark the Location, See Where You're Connected

Marker sites	How to connect	When to use it
N-terminal	Reaction of dye-NHS esters with amino	Most commonly used, preferred when N-terminal is unique
Lys sidechain	Reaction of dye-NHS esters with ε-amino acids	If there is more than one Lys, it may be randomly labeled
Cys side chain	Reaction of dye-maleimide with sulfhydryl groups	Highly specific, used when free Cys is present
C-suite	Special design required	used when the N-terminal is preserved intact
Internal special locator	orthogonal protection strategies	It needs to be designed to hit where it's meant to hit

3. labeled peptides that we can synthesize
Single Marker: Only one dye is attached, most commonly used
Double labeling: two different dyes, do FRET
Dyes + other modifications: e.g. with both phosphorylated or biotin
Quenching markers: e.g. EDANS/DABCYL FRET pairs

4. Synthetic Capabilities

Project	Capacity
peptide length	5-80 amino acids
Dye type	FITC, FAM, TAMRA, Cy3, Cy5, rhodamine, biotin, and others
Marker sites	N-terminal, Cys, Lys, internal fixed point
The purity option	Conventional (85-95%), high purity (95-98%)
Single-strip output	1-20 mg (depending on peptide length and dye)
form of delivery	Centrifuge tubes, syringes (keep away from light)
Periodicity	3-4 weeks (depending on markup complexity)

5. QC: Confirmation that the dye is attached
The quality control of fluorescent and dye-labeled peptides depends on whether the dye is successfully attached and whether the purity is up to the standard.

MS mass spectrometry: to see if the molecular weight increases the mass of the dye
HPLC: to see the purity, and also to see if there is any free dye residue

Why call us for fluorescently labeled peptides?

1. We've been doing this for 20 years
Fluorescence and dye-labeled peptides may sound like "a dye", but there are still a lot of tricks to achieve accurate site, complete labeling, and no quenching of fluorescence. Over the years, we have helped our customers to label peptides of various kinds: from the simplest FITC labeling to complex double-labeled FRET probes, from small peptides to long peptides, we have accumulated experience.

2. Marker site control, wherever you say
Some companies only do N-terminal labeling, so you can't tell if you're changing locations. We are different:
N-terminal labeling: routine operation, with NHS ester, good selectivity
Cys spot labeling: use maleimide, high specificity, suitable for peptides with free Cys
Lys marking: can be controlled, if there is only one Lys, it is a fixed point; if there are more than one, protection strategy can be designed
Internal fixed-point marking: orthogonal protection, point and shoot

3. A wide range of dyes, both common and uncommon
Common dyes: FITC, FAM, TAMRA, Cy3, Cy5, rhodamine, biotin
Specialty dyes: Alexa Fluor series, Texas Red, Pacific Blue, etc., can be customized
FRET pairs: EDANS/DABCYL, Cy3/Cy5, etc

4. Purity on demand, without waste of money
Routine pure (85-95%): sufficient for cellular imaging, flow
High purity (95-98%): quantitative experiments, FRET studies, more stable results

5. Data are complete and clearly labeled
We provide MS and HPLC data for each labeled peptide to tell you whether the dye is attached or not, and how pure it is.

6. From screening to application, all the way through
After finding a labeled peptide, there is often a need for more follow-up work: for example, amplification for animal imaging, development of reagent kits, etc. Science-Peptide can be seamlessly integrated, with the same project manager following the project through to the end, without the need for repetitive communication.

Where Fluorescently Labeled Peptides Are Used

Research areas	How it works	Recommended Dyes
cellular imaging	Depending on which cell the peptide enters and where it stays	FITC,TAMRA,Cy3
Flow cytometry	analysis combined with the proportion of positive cells that	FITC,Cy5
organizational positioning	looking at the distribution of peptides in animals	Cy5 (low tissue background)
FRET study	studying protein interactions or conformational changes	EDANS/DABCYL,Cy3/Cy5
receptor binding	Measurement combined with affinity	FITC,FAM
ELISA	capture or detection	Biotin
in vivo imaging	small animal live imaging	Cy5,Cy7

Delivery and quality control

Delivery: Lyophilized powder, centrifuge tubes or vials (protected from light)
Accompanying documents: COA (HPLC purity graph, MS mass spectra), synthesis report (optional)
Optional tests: peptide content, endotoxin
Customized Packaging: Separate and label according to your requirements

Before each fluorescent and dye-labeled peptide is shipped, we review the labeling, purity and molecular weight to ensure complete data and reliable quality.

Three real-life cases

Case 1: The cell-penetrating peptide program of a research institute

The customer was studying a 15 amino acid periplasmic peptide and wanted to see what cells it entered. We synthesized a FITC-labeled periplasmic peptide (N-terminal labeling) with a purity of >95%, and confirmed successful labeling by MS. Using flow and confocal microscopy, the customer was able to see clearly that the peptide had penetrated into a variety of tumor cells, and the membrane-penetrating efficiency was obvious.

Case 2: FRET Probe Program, Biotech, Inc

The customer needed a double-labeled peptide for protease activity detection: EDANS at one end and DABCYL at the other end, we precisely synthesized Cys-Peptide-Lys, and attached EDANS to Cys (maleimide method) and DABCYL to Lys (NHS ester method). The customer's test showed that the fluorescence recovery after digestion was obvious and the probe performance was satisfactory.

Case 3: ELISA development for a diagnostic reagent company

The customer was developing an assay that required a biotin-labeled antigenic peptide for antibody capture. We synthesized a biotin-labeled peptide (Cys site-labeled) with purity >95% and biotin ligation efficiency >90%. The customer successfully established an ELISA method using streptavidin plate with picogram sensitivity.

Talking about your fluorescently labeled peptide needs?

Whether you are doing cell imaging, flow, FRET or ELISA, if you need to label peptides, you can talk to us.

Give you a detailed quote and feasibility feedback within 24 hours.