Immunoglobulin fragments

Fragments of immunoglobulins are formed during enzymatic or chemical fragmentation (cleavage) of Ig molecules. Through the action of the enzyme papain, an antigen-binding fragment Fab (Fab = acronym for fragment antigen binding) and the crystallizable fragment Fc (Fc = acronym for fragment crystallizable) are formed. The fragments F(ab`)2 and Fc' are formed by the action of pepsin. Chemical degradation further leads to the cleavage of the disulfidic or some peptidic bonds between the chains. Some bacteria are also able to cleave immunoglobulins at this site via proteases. This leads to their reduced or complete ineffectiveness.