Fluorescence & Isotope Labeling


ALL Chemistry applies a wide variety of fluorescent labels. These labels can be incorporated at any desired position within your peptide. We have the capability to construct any viable fluorescent labeling peptide at your request. In addition, with high-quality isotope labeling specialists, ALL Chemistry provides comprehensive isotope labeling services. Our scientists have accumulated extensive experience in different types of isotope labeling technologies. All our efforts are focused on meeting customers' specific demands.


Fig.1 (A) non-natural fluorescent amino acids and (B) fluorescent organic probes.


Introduction of Fluorescence & Isotope Labeling


Fluorescent techniques are widely used in biological research due to their high sensitivity, selectivity, fast response time, flexibility, and experimental simplicity. Fluorescent tags or probes are ideal for many imaging and diagnostic applications and can also be used for biological sensors. In many cases, biological sensors consist of fluorescent versions of a particular protein. Peptides can be tagged with various fluorescent dyes at various positions. Fluorescent labeling of peptides can be used for microscopy, FACS, and in-vivo fluorescent imaging. Fluorescent labels or probes are ideal for many imaging and diagnostic applications. For Fluorescent peptides, the fluorescent dye can be attached to the N- or C-terminus or side-chain of amino acids such as lysine or glutamic acid. Peptides labeled with a single dye as tracers can be assayed by fluorescence. Fluorescently labeled peptides have been used to detect the activity of target proteins, and their developed high-throughput activity screening methods have been applied to drug screening and drug development for disease treatment target proteins. Therefore, the fluorescence modification of peptides is also an important component in the field of drug development.

Isotope labeling is a popular technique used to track the target molecule through a metabolic pathway, a reaction, or a cell. Radioactively labeled peptides provide a highly sensitive detection method without the common problems associated with other labeling methods, such as spurious fluorescence, enzymatic activity, or steric problems. Design your own radioimmunoassay or ligand binding study with I-125 and 3-H-labeled peptides. The principle of tracking the passage of an isotope is to replace the specific atoms of the target molecule with their isotope because the difference between the isotope and the original atoms is relatively easy to detect in the following experiment. The sequence the isotopic atom follows in the reaction or the cell's metabolic pathway can be determined by the position of the isotopes in the products. Custom peptides can also be synthesized with modifications by acetylation, phosphorylation, amidation, succinylation, butyrylation, and specific disulfide bridge cross-linking. The sequence the isotopic atom follows in the reaction or the cell's metabolic pathway can be determined by the position of the isotopes in the products.


Application of Fluorescence & Isotope Labeling


Applications for fluorescent peptides range from the study of peptide-protein interactions, enzyme activity assays, immunoassays, in vivo imaging, and the development of novel disease models. 

--For Subcellular Imaging and Tracking: Many discoveries in cell biology rely on making specific proteins visible within their native cellular environment. Combined with confocal or fluorescent microscopy, fluorescent-labeled peptides are used to identify specific targets.

--For in Vivo Imaging: Molecules that absorb in the near-infrared (NIR) region, 700–1000 nm, can be efficiently used to visualize and investigate in vivo molecular targets because most tissues generate little NIR fluorescence. Many novel peptide-based near-infrared (NIR) fluorescent probes have been developed for in vivo biomedical imaging,

--FRET for Enzyme Activity Detection: Proteolytic enzymes play important roles in infectious diseases and are ideal targets for developing novel therapeutics. Protease assays usually involve a fluorescent donor moiety and a quenching acceptor molecule, separated by a peptide containing the protease cleavage sequence. Since protease studies are most effective when FRET is combined with shorter peptides, peptide libraries are recommended for these experiments.


Fluorescence & Isotope Labeling Services at ALL Chemistry


ALL Chemistry can help you design and create the best labeled peptide or protein for your experimental application. Our chemists can help you determine the best label or modification based on your peptide sequence and experimental conditions. As an experienced chemical manufacturer, we are committed to providing high-quality products and services for scientists all over the world. To meet the detailed demands of customers, ALL Chemistry offers various types of isotope labeling services, including but not limited to segmental labeling, amino-acid selective labeling, and uniform labeling, such as the fluorescence resonance energy transfer and FRET assay. We provide several labeling pairs containing quench groups and Fluorescent Groups to mark the target proteins for researchers. The following table is a list of these fluorescent pairs:


Quench Group 

 Fluorescent Groups

 Excitation Wavelength (nm)

 Emission Wavelength (nm)





















 Tyr (NO2)




Table 1 Fluorescence Resonance Energy Transfer, FRET Assay




Forster Distance (nm) 





 (1): 5-(2-iodoacetylaminoethyl) aminonaphthalene-1-sulfonic acid

(2): N-(4-dimethylamino-3,5-dinitrophenyl) maleimide
(3) carboxyfluorescein succinimidyl ester
(4): 4,4-difluoro-4-bora-3a, 4a-diaza-s-indacene


 DDPM (2) 














 CF (3)

Texas Red 


Fluorescein Tetramethylrhodamine


Cy3 Cy5 >5.0


Rhodamine 6G Malachite Green 6.1
FITC Eosin Thiosemicarbazide 6.1-6.4







Table 2 The fluorescent Donor and Acceptor groups of the FRET Assay


Besides, ALL Chemistry also provides downstream and upstream services after protein yielding, purification, and modification. Please don't hesitate to contact us for more information about our protein and peptide modification services.


Advantages of Our Services


Optional Services: Amino acid Analysis and Sequencing

Excitation and emission spectra for each product, as well as analytical HPLC and MS analyses, are performed in every development cycle.

Deep knowledge and rich experience in biomaterial modification and conjugation. All Chemistry has a dedicated team of glycan experts to deal with complex carbohydrate research.

Different strategies are used to label peptides with dyes, and ALL Chemistry is proficient at all types of isotope labeling services.

With fast, economical, and efficient customized fluorescent protein products, ALL Chemistry will forever provide customers with cost-effective and perfect after-sales service.


Project Workflow


Evaluation → Experiment Design → Formal Quotation → Peptide Synthesis or Modification → Results → Delivery


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Telephone:+1 609 531 0668

Email:info@all-chemistry.com , sales@all-chemistry.com