Fab fragment

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One of the fragments produced by partial digestion of immunoglobulin with the proteolytic enzyme papain. It corresponds to an arm of the Y-shaped molecule and consists of an entire light chain paired with part of a heavy chain, complete with the antigen-binding site. Digestion of an IgG immunoglobulin molecule will thus yield two identical Fab fragments, representing the separated arms of the Y, and an Fc fragment, which corresponds to the stem of the Y and consists of the remaining regions of the heavy chains paired via the disulphide bond of the hinge region. Compare F(ab′)2 fragment.

Subjects: Chemistry — Biological Sciences.

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