Basic Structure of Antibodies

Antibodies are heterodimers. Antibody molecdules have a
common structurehaving four peptide chains.
It contains two identical light (L) chains, polypeptides of about 25,000 molecular weight, and
two identical heavy (H) chains, large polypeptides of molecular weight around 50,000 or more.

              Each light chain is bound to a heavy chain by a disulfide bond,
and by such noncovalent interactions as salt linkages, hydrogen bonds,
and hydrophobic bonds, to form a heterodimer (H-L).
Similar noncovalent interactions and disulfide bridges link the
two identical heavy and light (H-L) chain combinations to each other
to form the basic four-chain (H-L)2 antibody structure, a dimer of
dimers.