Immunoglobulins
Introduction · Immunoglobulins (Ig) or Antibodies: Gamma globulins produced by plasma cells, specific to antigens. · Respond to foreign proteins or complex molecules not accepted by the host. · Exist as approximately 20% of proteins in body fluids. · Functions: Antigen binding, complement fixation, facilitation of phagocytosis, neutralization of toxic substances. Classification · Based on the molecular structure of their heavy chains. · Five classes: IgA (α), IgD (δ), IgE (ε), IgG (γ), IgM (µ). · Each class has unique roles and characteristics. Immunoglobulin/Antibody Structure · Common biochemical structural configuration. · Glycoproteins made of light (L) and heavy (H) polypeptide chains. · Basic unit: Four polypeptide chains (two identical light chains and two identical heavy chains). · Simplest antibody: Y-shaped. Antigen Binding Fragment (Fab)