Introduction to Agglutinin

Agglutinin refers to a variety of plants, invertebrates and higher animals in the purification of glycoproteins or binding sugar protein, because it can agglutinate red blood cells (blood type substances), hence the nameAgglutinin. Commonly used as phytoagglutin (PNA), usually named after its extracted plants, such as Conconvalina (Conconvalina, ConA), wheat germ agglutinin (WGA), peanut agglutinin (Peanut agglutinin, PNA) and soy agglutinin (Soybean agglutinin, SBA), etc., Agglutinin is their general term.Agglutinin is not a source or participates in the immune response product, and the reason why they are incorporated into this book is due to some of the "affinity" properties of Agglutinins that can be used by immunocytochemistry techniques. Thus, Ponder (1983) suggests that it should be called "Agglutinin histochemistry" and can not be called "Agglutinin immunohistochemistry".

The type of Agglutinin

The Agglutinin can be classified according to the specificity of sugar, the molecular structure, the binding site and its function. Animal Agglutinin is divided into C-type Agglutinin, S-type Agglutinin, P-type Agglutinin, I-type Agglutinin and pentamine (Pentraxins) by molecular structure. C-type Agglutinin is Ca2 + -related Agglutinin; S-type Agglutinin is a Agglutininthat specifically recognizes the β-galactoside bond; the P-type Agglutinin is a Agglutinin that specifically recognizes 6 mannose phosphate; I- Agglutinin is a Agglutinin similar to immunoglobulin; Pentaoxins are Agglutinins with five subunits.

The nature of Agglutinin

So far in the invertebrate body found in the Agglutinin are glycoproteins, sugar covalent bond into the form of Agglutinin, the type of sugar mainly include mannose, glucosamine, galactose, and rare xylose, arabinose. Animal Agglutinin contains the type of sugar and plants, microbial Agglutinins contained in different types of sugar, Agglutinin in the protein part of the main by the aspartic acid, serine and threonine composition, rare sulfur-containing amino acids. The metal ions associated with partial Agglutinin activity are often Ca and Mg, which are necessary for the binding or agglutination of many sugars. An indispensable condition for the aggregation of many Agglutinins (such as C-type Agglutinins) is the presence of Ca. In the Limulin, it is necessary to carry out the physiological activity in the form of calmodulin. In Anthocidariscr assispina, Ca is the effect of Agglutinin molecular conformation: Ca affects oyster Agglutinin by changing the protein configuration , Rather than directly involved in ligand binding. Some people think that Ca through the ionic bond and shuttle and other effects to stabilize the structure, enhance the interaction of hydrogen bonds and hydrophobic groups.

Agglutinin agglutination reactions are often inhibited by monosaccharides, while others require certain disaccharides, trisaccharides or polysaccharides, the sensitivity of the inhibition is quite different. Some of the typical effect agglutinins are susceptible to partial carbohydrates in the corresponding blood type substances, such as the agglutinin of type A blood antigen, which is inhibited by N-acetyl-D-galactose; the O-type agglutinin is treated with L-fucose Suppressed. The specificity of Agglutinin-binding carbohydrates varies. The combination of a few Agglutinins is quite narrow. The use of proteases, such as trypsin, streptomycin and other mildly to deal with Agglutinins, can increase the sensitivity of agglutination activity, some additives, metal ions also affect the activity of Agglutinin.

Characteristics of Agglutinin

Agglutinin has many characteristics, and we briefly mention some of its properties related to the application of immunocytochemistry techniques. We know that the biofilm contains a certain amount of carbohydrates, mainly in the form of glycoproteins and glycolipids. The most important feature of Agglutinins is that they recognize the complex carbohydrate structure in glycoproteins and glycopeptides, especially in the cell membrane, the carbon lipide determinants on the cell membrane surface. A Agglutinin has the ability to bind specifically to a particular specific glycosyl group, such as concanavalin and alpha-D-glucopyranosyl (α-D-Mannopyranosy); maltose and N-acetyl Glycosaminoglycans (N-acetylglucosamine); and bean agglutinin binds to N-acetylglucosamine (see Table 6-1 in this chapter). Thus, Agglutinins can be used as a probe to study specific glycosyl groups on the cell membrane. On the other hand,Agglutinins have a multivalent binding ability that binds to tracers such as fluorescein, biotin, enzymes, colloidal gold, and ferritin to show their binding sites at the level of light and / or electron microscopy.

Application of Agglutinin

It is generally believed that specific glycosyl groups on the cell membrane can be used to distinguish the type of cell and reflect the changes in cell differentiation, maturation and tumor cell changes. In some particular cases, the performance of their cell-bound Agglutinins can be estimated in advance, such as the specificity of the double lentilene in the blood type A substance, the arsenic agglutinin in the blood type O substance 2-L-fucose Specificity, however, in the vast majority of cases, the nature of the carbohydrate determinants identified by Agglutinins, the nature and function of the molecules carrying the determinants are fully investigated by experimental experience.

The significance of Agglutinin research

Agglutinin is present in plants and plants. The most important feature of Agglutinins is the ability to recognize glycoproteins and glycolipids, especially in the complex membrane of the carbohydrate structure, that is, the cell membrane surface of the sugar. A Agglutinin has the ability to bind specifically to a particular specific glycosyl. Thus, Agglutinins can act as probes for studying cell membrane structures. Agglutinin in the invertebrate blood has a variety of biological activity, you can choose to agglutinate a variety of cells, specific agglutination of tumor cells, etc., is one of the important immune body defense factors. On the other hand, Agglutinin has a multivalent binding ability, can be combined with fluorescein, enzyme, biotin, ferritin and colloidal gold without affecting its biological activity, can be used for light microscopy or electron microscopy level of immunocytochemistry , In the exploration of cell differentiation, proliferation and malignant transformation of the biological process, showing tumor-related antigen substances, as well as the diagnosis of cancer and other aspects of a certain value. In addition, phytohemagglutinin also plays an important role in plants, such as the role of germination in the seed germination process; the mitogenic factor as a plant embryo; the protective function in the control of crop pests and so on. Studying the specificity of Agglutinins helps to understand life phenomena or pathological changes at the molecular or atomic level.