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Protein Labeling Service

KMD Bioscience makes consistent efforts on recombinant protein expression and antibody development to present you with clean and reproducible results. Under the support of our improved protein modification platform, scientists in KMD Bioscience can provide you with a range of protein modification services, covering enzyme conjugation, fluorescent labeling, isotope labeling, PEG labeling, biotinylation, magnetic beads conjugation, and quantum dots labeling services.


Enzyme Conjugation Service:


Enzyme labels often refer to horseradish peroxidase (HRP) and alkaline phosphatase (AP), which are often used to label antibodies and then used as enzyme-linked immunosorbent assay (ELISA). HRP consists of multiple isozymes with a molecular weight of 400,000 and a protein isoelectric point of pH 3-9. the optimal pH for enzyme catalysis will be slightly different due to the hydrogen donor, but mostly at pH 5. HPR is more suitable for rapid chromogenic reactions. Adding a substrate to the ELISA, the OD 450 comes to 1.8-2.5 in 5-10 minutes. AP is more suitable for slow chromogenic reactions, the color development reaction time can be about 4-8 hours, and the catalyzed yellow compound is more stable and is ideal for quantitative detection of enzymatic kinetics. The HRP and AP used by KMD Bioscience are both from Sigma and we have  extensive experience in protein quantification. In order to ensure  optimal protein labeling, we are able to design the most appropriate protocol to reach the protein and enzyme label ratio of 1:1.

You can also gain access to the biotin labeling services offered by KMD Bioscience. Biotin can be used as a fusion tag with target protein for recombinant expression for subsequent purification and screening, for example, biotin labeling has very high screening efficiency when phage display library screening and  it is also very suitable for tissue-specific expression monitoring of IPC, a protein with the Biotin labeled can be directly applied to IP and magnetic beads sorting.


Isotope Labeling Service:


Protein isotope labeling is a very classic technique for protein tracing and proteomics quantification. Compared to the in vitro labeling techniques, isotope labeling belongs to in vivo labeling which is replaced corresponding amino acids in cell culture medium by essential amino acids labeled with native isotopes(light)or stable isotopes(heavy); after cultured 5-6 doubling-time, the stable isotope-labeled amino acid can completely integrate into the newly synthesized protein of the cells to replace the original amino acid. The lysed proteins of differently labeled cells were mixed in the proportion of the number of cells or the same amount of protein, after separation and purification, detected by mass spectrometry. The relative quantitation was performed based on the comparison of the area of two isotopic peptides in the first-class mass spectrum.KMD Bioscience has our protein expression platform combined with a cell culture platform which can provide our clients with 13C,15N,15N-13C,35S and 3H protein isotope labeling services.

The protein isotope labeling service can also use 125I and 131I. Tyrosine in the protein can be labeled by HPLC or open column chromatography (depending on the properties of the iodinated molecule), with the free iodine removed and the radioactive iodine labeled onto proteins and other molecules, and the radioactive iodine is used as a tracer or probe. Generally, LC is used to detect the labeled products to ensure that the percentage of free iodine is less than 5%.


Fluorescent Labeling Service:


Fluorescent dye-labeled protein/polypeptide is a common in vitro protein labeling technology, besides fused expression GFP GYP and other fluorescent proteins, the target protein can be directly labeled by fluorescent dye for live tracing, cell sorting, etc. KMD Bioscience can provide Fluorescent dye labeling including FITC, FAM, RBITC, Colloidal gold labeling including Co-Au, Cy3, Cy5, Cy5.5, Cy7, and APC, PE, and Alexa Fluor 350, Alexa Fluor 488, Alexa Fluor 555, Alexa Fluor 594, Alexa Fluor 647. For each peptide or protein that needs to be labeled, our scientists will evaluate the physicochemical characteristics of the polypeptide or the protein in detail, such as peptide labeling, linker length, and type cross-linking position to give you reliable assistance.


Quantum Dots Labeling Service:


We provide quantum dots labeling services with inorganic structure ZnCdSe/ZnS as the core:


Carboxy and amino water-soluble quantum dots (Figure A): They are obtained by surface modification of oil-soluble quantum dots with a polymer and can be uniformly dispersed in an aqueous solution (such as borate buffer, PBS buffer solution), the surface carboxyl group and the amino group are reactive, the particle diameter ranges from 12 to 18 nm.

Oil-soluble quantum dots (Figure B): By coating the surface of the inorganic structure ZnCdSe/ZnS with a hydrophobic ligand, the quantum dots can be uniformly dispersed in a non-polar organic solvent (such as hexane, toluene, chloroform), which is easy to perform. The particle size ranges from 5 to 10 nm. After encapsulation, oil-soluble quantum dots can be used as an LED backlight source to enhance the display color gamut. In addition, after the surface modification of the oil-soluble quantum dots to introduce active groups, they can be conjugated with biomolecules, which can be used in biomarkers/detection, high-throughput coding, in vivo imaging, and dynamic tracing.



Beads Conjugation Service:


Magnetic nanospheres (MNS) are nanospheres series products with high molecule polymer as core, coated with magnetic nanoparticles, and with functional groups (carboxyl group, amino group). The products have the characteristics of good dispersibility, fast magnetic response, abundant surface functional groups, and quick and easy separation. It is widely used in nucleic acid purification, protein purification, affinity chromatography, cell sorting, immunoassay and clinical diagnosis and other biomedicine research field.


PEG Labeling Service:


KMD Bioscience also offers PEG labeling services with different molecular weight. Please find more forP EG modification services. 


How to Order?

If you have any questions regarding our services or products, please feel free to contact us by E-mail: or Tel: +86-400-621-6806