Epitope is where the antigen is

Most of them are present on the surface of the antigenic substance, and some are present inside the antigenic substance, which must be treated by enzymes or other means before being exposed.

The center of activity, generally on the surface.

Where is the antigen of the bacteria, and what determines the antigen of the bacteria.

The main antigens of Enterobacteriaceae bacteria have complex structures, mainly including bacterial (O) antigen, flagellar (H) antigen and surface antigen

1) 0 antigen. It is a component of the bacterial cell wall, and its chemical composition is lipopolysaccharide. The lipopolysaccharide molecule is a three-layer structure centered on the core polysaccharides, the core polysaccharides of all genera of bacteria in the Enterobacteriaceae family are the same, the inner side of the core polysaccharide is lipid A, which is the toxic component of endotoxin, and the outer side of the core polysaccharide is a polysaccharide chain composed of repeated oligosaccharides, which determines the specificity of the 0 antigen.

2) H antigen. It is a heat-tolerant protein antigen, and the specificity of the H antigen is determined by the amino acid sequence and spatial configuration on the flagellin polypeptide chain.

3) Surface antigen. It is a heat-intolerant polysaccharide antigen wrapped around the outside of the O antigen, and the specificity of the surface antigen is determined by the structure of the mucus or capsular polysaccharide, and the surface antigen has different names in different bacterial genera, such as the K antigen of Escherichia coli, the VI antigen of Salmonella typhi, and the K antigen of Shigella.

The 0 antigen and the H antigen are the basis for the serogrouping and typing of the Enterobacteriaceae family, and the reaction between the O antigen and the corresponding antibody can be blocked in the presence of surface antigen, and the blocking effect of the surface antigen can be eliminated by heat treatment.

1 Pinyin 2 English references.

3 Remarks Kàng yuán jué dìng cùantigenic determinant epitopes are special chemical groups that exist on the surface of an antigen molecule and determine the specificity of that antigen. In this way, the antigen binds to the antigen receptor of the corresponding lymphocytes and activates the lymphocytes to cause an immune response. The antigen recognition receptor on the surface of lymphocytes distinguishes between "self" and "non-self" by recognizing epitopes. The specific binding of the antigen to the corresponding antibody is also done by epitope. Therefore, epitopes are the material basis for the specificity of immune responses and immune responses.

An epitope is a small portion of an antigen molecule that is equivalent in size to the binding site of the corresponding antibody. They can consist of 5 7 amino acids, monosaccharides or nucleotides. The nature and spatial configuration of each epitope determine a specificity and can bind to an antibody.

Multiple epitopes determine the specificity of multiple antigens. An antigen molecule can have one or more different epitopes that vary in composition and spatial tartarial arrangement, thus determining the specificity of the antigen. The total number of epitopes in an antigen molecule that can bind to the corresponding antibody molecule is called the antigen binding valence.

There are non-functional, covert antigen-determining clusters inside the antigen molecule. Only when exposed to the surface of antigenic molecules under the treatment of physicochemical factors, can it play the role of epitope.

It can be composed of a continuous sequence (protein primary structure) or a discontinuous protein three-dimensional structure, a special chemical group that determines antigenicity, also known as an epitope. Epitopes are mostly found on the surface of antigenic substances, and some are found inside antigenic substances and are exposed only after being treated by enzymes or other means. A natural antigenic substance can have multiple and multiple determinants.

The larger the antigen molecule, the greater the number of determinants.

Chinese name: epitope.

Foreign name: antigenic determinant Synonym: antigen epitope.

Composition: 6-12 amino acids or carbohydrate group composition.

Hello landlord!

Yes, the epitope is a special group that determines the antigenicity on the surface of the antigen, and the general epitope is composed of 6 12 amino acid polypeptides or carbohydrate groups, which can be composed of a continuous sequence (protein primary structure) or a discontinuous protein three-dimensional structure.

Among them, antigens are divided into complete antigens and haptens. The essence of complete antigen is protein or glycoprotein, hapten is mostly polysaccharides, lipids and some small molecule chemicals, generally sugar chains, lipid chains or special chemical function groups, haptens enter the body and bind to proteins in the body to become complete antigens, that is, after the hapten and protein are combined, the original hapten molecule becomes a determinant.

In general, as far as the high school class requirements are concerned, about the chemical nature of the antigenic determinant, it is enough to answer the protein or glycoprotein. But if you want to be more complete, you can answer them all. Different regions have different requirements, so it's best for the landlord to ask the teacher!

The general epitope is composed of 6 12 amino acids or carbohydrate groups, which can be composed of continuous sequences (protein primary structure) or discontinuous protein three-dimensional structure.

For antigens with multiple epitopes, the binding of more than one antibody to the immune response is often not sufficient to complete the response.

If so, people will not have acquired immunity, and only because there is an antigen determinant family, the body's antibodies will immediately respond to the invading antigen. However, if it is an antigen with multiple antigenic determinants, then it is often different immunogenicity.

For example, the surface of Streptococcus pyogenes has an antigenic determinant that closely resembles the surface structure of a substance on a heart valve; When the body is infected with the virus, the immune system produces antibodies that attack not only the virus, but also the heart valves. As a result, while the virus was eradicated, the heart was also damaged, resulting in rheumatic heart disease.

Epitopes and antibodies are structurally one-to-one.

Evidence: Immunology explicitly states that "the binding of an antibody to an antigen is specific because the antibody has a binding site corresponding to the epitope (antigen binding cluster)". Specificity refers to the fact that an epitope can only bind specifically to the corresponding antibody or effector T cells.

So it's a one-to-one correspondence.

However, an antigen corresponds to more than one antibody, as an antigen may have several different epitopes. Evidence: "The specificity of an antigen is determined by specific chemical groups on the surface of the molecule, which are called epitopes", and an antigen may have more than one specific chemical group and therefore may have several different epitopes.

Antigen-antibody binding must have a "contact-isomerism-binding" process, in which they bind through intermolecular structural forces (as they seem to be called structural stresses).

The definitive answer can be found in Immunology.

Antigen and epitope are two concepts.

A protein is an antigen, but there can be several epitopes. That's why there is cross-reactivity of antibodies. That is, one antibody may react with several antigens. But an antibody recognizes only one epitope.

There is a lot of literature. I found a very basic review of the literature that analyzed in detail the effects of epitopes, including changes in the structure of the molecular mirror image, on antibodies. Hope that helps.