anti-Immunoglobulin G (IgG) secondary antibodies

Each IgG is composed of four peptide chains -- two γ heavy chains of about 50 kDa and two light chains of about 25 kDa - with two antigen binding sites. Hence, IgG antibodies are large molecules of about 150 kDa. The two heavy chains are linked to each other and to a light chain each by disulfide bonds. The resulting tetramer has two identical halves which together form the Y-like shape.

There are four IgG subclasses (abbreviated simply as IgG1, 2, 3 and 4) in humans, named in order of their abundance in serum (IgG1 being the most abundant). A cleavage reaction using papain can result in Fc and Fab fragments and a Fc fragment. Proteolytic enzyme pepsin cleaves below the hinge region, forming a F(ab')2- and a pFc' fragment. The F(ab')2 fragment can be split further into two Fab' fragments by reduction.

IgG antibodies are involved in the secondary immune response (IgM is the main antibody involved in primary response). IgG can bind pathogens, like for example viruses, bacteria, and fungi, and thereby protects the body against infection and toxins. Comprising up to 80% of the antibodies found in the human body, IgG is the smallest, yet most abundant human antibody, and that of other mammals. IgG can be found in all bodily fluids, and is the only antibody that can protect a foetus by passing through the mother's placenta.

For research IgG is one of the predominant tools due to its versatile application possibilities. It can be produced utilizing donkeys, mice, rats, rabbits, chicken and goats. The lists below contains a large variety of host and specificity combinations for IgG heavy and light chain (H/L) antibodies as well as for their fragments Fc and F(ab).