Definition of antibody
An antibody is a specialised defence protein synthesised by the vertebrate immune system. These small structures are actually composed of 4 different protein units. The ends of the molecule are variable and can be adapted to bind to any molecule. The shape is determined by the antigens in the system that are causing damage. Special immune cells detect these antigens and create a reciprocal antibody. This generalised structure is repeated many times to flood the system with antibodies. These proteins bind to the antigens and surround them, preventing further spread or infection.
In this way, a organism can identify the “self” from the “non-self”. For example, the surface of bacterial cells has certain proteins and carbohydrates, which can be identified by the immune system. B-lymphocytesa cell special immune cells create and release antibodies that attack invading bacteria. An antibody attached to a bacteria not only prevents it from completing normal processes, but also helps white blood cells to eat the bacteria. These macrophagesas they are known, identify foods based on the antibody tail.
In the bloodantibodies account for about 20% of the total protein. This is a very significant amount. Although a single antibody may be very small, an organism must have many antibodies to fight the many types of antigens present in the system. In addition, many of each type are needed. Often many antibody molecules are needed to target and identify a large bacterium. The virusesAlthough they are smaller, they are much more abundant and need equal amounts of antibodies to quell them.
While other organisms often have immune systems based on similar concepts, the term antibody and the structure described below are unique to mammals. An antibody can also be referred to as immunoglobulina term that describes a protein used in an immune function. The most common antibody is immunoglobulin G (IgG) in mammals. Antibodies, if they exist at all, are not well understood in invertebrates and plants. While these organisms are also known to have immune systems, it is not entirely clear how they function.
Structure of antibodies
Above is a typical antibody. Note that the structure is actually made up of 4 different protein chains. There are two heavy chains and two light chains. The two heavy chains are connected by a disulfide bondwhich exists between two sulphide atoms present in the amino acids of each chain. The light chains are attached to the sides of the heavy chain through a series of non-covalent bonds and weak interactions.
Each chain is divided into two regions, the constant region and the variable region. The constant region is produced directly from the DNA and is the same in all antibody molecules of the same type. The variable region is the part of the antibody that changes according to the antigen present. B-lymphocytes are in charge of a complex process that matches the variable region to the antigen and then mass-produces the correct antibody.
It is the variable region that has a binding sitecapable of binding to the antigen. The binding site is specific because it is designed to bind only to the desired antigen. It does this by being as compatible as possible with the antigen. If the antigen is hydrophobicso is the binding site. If the antigen is negatively charged, the binding site will be optimally positively charged to help bind the antigen. In addition, the entire shape of the head of the antibody is specifically tailored to the shape of the antigen. This ensures that the antibody is specific to the antigen. The constant region of the antibody can come in various forms and can be assembled into larger complexes with different shapes.
Action of antibodies in autoimmune diseases
In some cases, the antigen is so close to a molecule produced by the body that the immune system ends up attacking itself. This is known as autoimmune disease. The immune system, when presented with an antigen, forms a defence. In these cases, the antigen is usually a protein. The protein is similar to a protein produced by the body. While the antibody-forming system can be very specific, it cannot accurately identify two molecules that have the same shape. Therefore, even if the molecules are truly “self”, it may still end up attacking them.
Autoimmune diseases can be caused by a number of conditions. Some include viruses, such as HIV, which cause the immune system to target itself. Other autoimmune diseases, such as certain forms of diabetesmay be caused by the immune system’s attack on the pancreas, a organ insulin-secreting organ. There has been some research that may link this autoimmune reaction to proteins found in animal products. Although plant proteins have evolved on a completely different trajectory, humans and farm animals share many of the same genes. This means that they produce many of the same proteins. If these proteins leak into the body without being broken down, they could be identified as an antigen.
Upon seeing this antigen, the immune system will create an antibody to contain it. These antibodies will be produced en masse and sent throughout the body to attack any protein in the same way. This can cause a serious problem for your body. Let’s say you have just eaten a hot dog. All the parts of a pig and a cow are used to create hot dogs. Needless to say, you will probably get proteins that originated from the pancreas, the cartilage or other organs of the animal. Because their proteins are so similar to yours, your body will start to have an immune reaction where these proteins are present. This could be one of the main causes of diseases such as diabetes, arthritis and possibly even conditions such as multiple sclerosis.
Use of antibodies in analytical techniques
An antibody can also be a very useful tool in the laboratory. Because an antibody is so specific and binds strongly under certain conditions, antibodies are used in various applications to screen an antibody in a variety of ways. solute of a solution. In the column chromatographyare used to bind to the passing solute molecules. As the solution is drained, the antibody retains the solute. A different solution, with a different pH, can be washed over the antibody medium, and the antibody will change shape and release the solute.
Another common use of an antibody in the laboratory is to detect certain substances. An antibody binds to another protein, which is used to create a visible molecule. When the antibody is in the presence of the antigen, the antibody changes shape and activates the enzyme. This action creates visible molecules and can be detected visually or by computer. This allows scientists to detect very small samples of a substance at a relatively low cost. This can be used to diagnose diseases, test products and test the safety of consumer products.