Antibodies

• Antibodies are globular proteins with a quarternary structure
• They have two heavy polypeptide chains and two light polypeptide chains blinded together by disulphide bonds
• Each polypeptide has a variable region and a constant region. The constant region determines the mechanism used to destroy the antigens. The amino acid sequence is different in each variable region of the antibody
• The anti-body attaches to an antigen in the variable region to form an antigen-antibody complex
• The hinge region allows the antigen-binding site to be placed at different angles
• Antibodies do not directly destroy antigens, but prepare them for destruction
• Antibodies cause agglutination - clumping of cells so phagocytes can find them and destroy them
• Antibodies serve as markers to stimulate phagocytosis