is similar to the sequence of antibody in the same class.The constant region is the part of the antibody that binds to mast cells,complement,and protein A.Protein A is a bacterial cell wall protein isolated from Staphylococcus aureus which binds to the Fc (Fragment-crystallizable)fragment of the antibody molecule.This protein can be used in affinity chromatography to purify antibodies. Papain digestion cleaves IgG molecules into two fragments which can be separated by carboxymethyl cellulose ion exchange chromatography.One fragment will crystallize spontaneously.This fragment is called Fe fragment (fragment-crystallizable)and is deficient in antigen-binding ability.The Fc fragment has a molecular weight of approximately 50,000 and a sedimentation coefficient of 3.5S.The Fc fragment is the constant region of the heavy chain with a COOH terminus end.The second fragment is fragment antigen-binding (Fab).The molecular weight and sedimentation coefficient for the Fab are similar to Fc fragments.An IgG molecule consists of 1 Fc and 2 Fab fragments.Each Fab fragment consists of the amino terminal half of the heavy and light chains.It was possible to predict the structure of IgG molecule with Papain (Fc and Fab)fragments and sulfhydryl reagents which split the IgG molecule into light and heavy chains Antibodies specifically combine with a small segment of the antigen called the antigenic determinant or epitope to form an antigen-antibody complex. The antigen-antibody reaction is characterized by specificity.If a mouse is injected with goat albumin,the mouse will produce antigoat albuminis similar to the sequence of antibody in the same class. The constant region is the part of the antibody that binds to mast cells, complement, and protein A. Protein A is a bacterial cell wall protein isolated from Staphylococcus aureus which binds to the Fc (Fragment-crystallizable) fragment of the antibody molecule. This protein can be used in affinity chromatography to purify antibodies. Papain digestion cleaves IgG molecules into two fragments which can be separated by carboxymethyl cellulose ion exchange chromatography. One fragment will crystallize spontaneously. This fragment is called Fc fragment (fragment-crystallizable) and is deficient in antigen-binding ability. The Fc fragment has a molecular weight of approximately 50,000 and a sedimentation coefficient of 3.5S. The Fc fragment is the constant region of the heavy chain with a COOH terminus end. The second fragment is fragment antigen-binding (Fab). The molecular weight and sedimentation coefficient for the Fab are similar to Fc fragments. An IgG molecule consists of 1 Fc and 2 Fab fragments. Each Fab fragment consists of the amino terminal half of the heavy and light chains. It was possible to predict the structure of IgG molecule with Papain (Fc and Fab) fragments and sulfhydryl reagents which split the IgG molecule into light and heavy chains. Antibodies specifically combine with a small segment of the antigen called the antigenic determinant or epitope to form an antigen-antibody complex. The antigen-antibody reaction is characterized by specificity. If a mouse is injected with goat albumin, the mouse will produce antigoat albumin