Because of its shape, these immunoglobulins are able to start the lysis of cells more efficiently than the other immunoglobulins. Due to this, IgM are often the first immunoglobulins created after an infection or injection has occurred. This immunoglobulin is the first class to be synthesized by the fetus and thus can be used as a marker for infections. They are able to agglutinate antibodies and are well equipped to handle antigens with repeated patterns. IgM also includes isohemagglutinins which causes incompatibility within the ABO blood groups. IgM is composed of five four-chain structures composed of two heavy and two light chains each. These five units are joined together using J chains and disulfide bonds to form a pentameric molecule which weighs about 900, 000 Da. The bonds that hold the pentameric molecule together separate with the use of reducing agents. This molecule only has five sites where antigens can combine, known as …show more content…
This makes the molecular weight for the monomeric for is approximately 165,000 Da and the molecular weight for the dimeric form is approximately 400,000 Da. The monomeric IgA is one unit consisting of the four chains. This molecule is not able to bind. The dimeric IgA molecule contains two of the four chain unites that are joined by the J chains. There are two subclasses of IgA, IgA1 and IgA2. IgD molecule contains two δ heavy chains and two light chains, either λ or κ. The molecular weight is approximately 180,000 Da. It has a long hinge region which is thought to make its presence low in the serum. It functions as antigen specific B cell receptors on mature B cells, like IgM. Mature B cells are marked by this presence of IgD molecules. It has also been shown to stop self-reactive antibodies during the developmental phase. IgE contains two ε heavy chains and two light chains, either λ or κ, and it contains an extra CH domain. Together, the molecular weight is about 200,000 Da. Compared to the other classes of immunoglobulins, IgE experiences the shortest half-life. However, once an IgE molecule binds to a receptor, it can remain for weeks and sometimes months on the cell while it is waiting for the antigen to reappear. It has been shown to protect the body against parasites causing an inflammation