Protein/Antibody Labeling Customized Service
In order to research the property, purity, structure and function of protein and observe & detect the antigen-antibody specific reaction, the substances with the features of easy detection and high sensitivity are usually chosed as the labels to label the antigen. Then the color variations and spectral changes produced by the enhancement and amplification effect of these labels are measured to achieve the purpose of the research. In certain conditions, the proteins/antibodies can bind with the labels to form labeled proteins/antibodies by employing the special physical and chemical properties of amino acid residues of the proteins/ antibodies, and the principle was shown below.
figure 1. The principle of antigen labeling
Enzyme labeling, biotin labeling, fluorescent labeling, C13 and N15 whole protein labeling etc. often were used in protein labeling.
Enzyme labeling, biotin labeling, fluorescent labeling, immune colloidal gold labeling etc. often were used in antibody labeling.
Several common labeling methods were introduced for everyone below:
1) Enzyme labeling: Enzyme labeling includes enzyme-labeled antigens, enzyme-labeled antibodies and enzyme-labeled SPA, etc.. The success of immune enzyme technology or not are directly affected by the quality of enzyme label, which is called the key reagents. The most commonly used enzyme labeled substance is the enzyme-labeled antibodies, which are made by connecting the enzyme and the specific antibodies by the appropriate method. The quality of enzyme-labeled antibodies mainly depends on the purity, activity and affinity of enzymes and antibodies. The second factor is a good preparation method. At present, the commonly used high-quality enzymes, such as horseradish peroxidase, alkaline phosphatase, glucose oxidase, β-D-gal enzyme, can be supplied in domestic. While the high-quality antibodies can be obtained by extraction and purification. Further more, the easy preparation methods are selected, with high yield, little influence in the activity of the conjugates and almost no interference substances.
2) Biotin labeling: Biotin is widely distributed in the tissues of animals and plants. The α and β forms derived from the yolk (α) and liver tissue (β) with same biological activities, can be synthesized artificially at present. Biotin, also known as coenzyme R or vitamin H, can participate in a variety of carboxylase reaction in the form of coenzyme in the body, The molecular weight of 244.31. It has two rings structure. For them, the I ring-the imidazolone ring, is the main site for binding with the avidin; II ring-the thiazole ring, has a valeric acid side chain, of which the terminal carboxyl is the unique structure to combine antibodies and other biological macromolecules.
The commonly used activated biotins were shown below:
Activated biotin for labeling protein amino groups: BNHS;
Activated biotin for labeling protein aldehyde groups: BHZ and BCHZ;
Activated biotin for labeling protein thiol groups: MPB;
Activated biotin for labeling protein nucleic acids: photobiotin, biotin deoxynucleoside triphosphate, BNHS and BHZ;
3) Fluorescent labeling: Fluorescence is a kind of photoluminescence phenomenon. When a substance was irradiated by a certain length incident light, it can absorb light energy and enter the excited state, then it glowed a emission light longer than Incident light. And once the incident light was stopped, the luminescence phenomenon also immediately disappeared. The emission light with this feature is called fluorescence. The fluorescence characteristics variation after adsorpting or covalently binding the fluorescent dyes with a molecular group of the study objects, can reflect the properties of the study objects.
Commonly used fluorescent markers are: FITC (green), RB200 (red), TRITC (red), Cy3 (green), Cy5 (red) and so on.
4) Immune colloidal gold labeling: Immune colloidal gold labeling was established in 1971. Over the past 10 years, as the nitrocellulose membrane (NC), etc. were used as the solid carrier and the antigen or antibody labeled with colloidal gold reacted on the membrane with specific ligands, the rapid gold-labeled immunofiltration technology and gold labeled immunochromatography were established and widely used in immunological detection for infectious diseases, cardiovascular disease, rheumatism, autoimmune diseases.
Colloidal gold is the gold micro-particles (0-100nm) dispersed in the solution, usually refers to the colloidal suspension of gold nanoparticles, which can be used to label the proteins (antigens, antibodies or SPA, SPG). With the characteristic of high electron density, the dark brown particles can be seen at the junction of gold labeled antigen and antibody complexes under the microscope. When these labels gathered in large quantities, red or pink spots appeared in the carrier film, which can be used for semi-quantitative or qualitative measurement of antigens or antibodies.
The test principle is to restore the HAuCl4 into a certain diameter of gold sol particles to label SPA or antibodies. This technology is often used in immunoblotting, immunohistochemical localization or rapid immuno filtration, immunochromatographic assay.
Wuhan Cloud-Clone Corp. has carried out protein/antibody labeling customized services, a variety of different labels can be chosen according to your demands. Hope this convenient, simple and time saving service can bring you a better user experience!
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