Purified by Ion Exchange Chromatography. Human IgG purified protein (Immunoglobulin G) are antibody molecules. Human IgG is composed of four peptide chains - two heavy chains ? and two light chains. Human IgG has two antigen binding sites. Other Immunoglobulins may be described in terms of polymers with the IgG structure considered the monomer. Human IgG typically constitutes 75% of serum immunoglobulins. Human IgG molecules are synthesized and secreted by plasma B cells. Applications: Suitable for use as antigen or ligand in immunochemical reactions, as a control or standard in immunological assays, and conjugation.