Recombinant Human IgG4-Fc Protein (aa 99-326)

As a monomeric immunoglobulin that is predominately involved in the secondary antibody response and the only isotype that can pass through the human placenta; Immunoglobulin G (IgG) is synthesized and secreted by plasma B cells; and constitutes 75% of serum immunoglobulins in humans. IgG antibodies protect the body against the pathogens by agglutination and immobilization; complement activation; toxin neutralization; as well as the antibody-dependent cell-mediated cytotoxicity (ADCC) . IgG tetramer contains two heavy chains (50 kDa) and two light chains (25 kDa) linked by disulfide bonds; that is the two identical halves form the Y-like shape. IgG is digested by pepsin proteolysis into Fab fragment (antigen-binding fragment) and Fc fragment ("crystallizable" fragment) . IgG1 is most abundant in serum among the four IgG subclasses (IgG1; 2; 3 and 4) and binds to Fc receptors (FcγR) on phagocytic cells with high affinity. Fc fragment is demonstrated to mediate phagocytosis; trigger inflammation; and target Ig to particular tissues. Protein G or Protein A on the surface of certain Staphylococcal and Streptococcal strains specifically binds with the Fc region of IgGs; and has numerous applications in biotechnology as a reagent for affinity purification. Recombinant IgG Fc Region is suggested to represent a potential anti-inflammatory drug for treatment of human autoimmune diseases.

Generally, lyophilized proteins are stable for up to 12 months when stored at -20 to -80°C. Reconstituted protein solution can be stored at 4-8°C for 2-7 days. Aliquots of reconstituted samples are stable at < -20°C for 3 months.