The prime in the F(ab') means, that this fragment differs from the Fab-fragment
generated by Papain cleavage. F(ab')is generated by Pepsin cleavage behind the
disulphide bridges in the hinge region followed by mild reduction (with cystein
or DTT) and consists of an a-chain (which is identical with the a from Fab (and
the light chain of the antibody)) and a b'-chain, which is slightly longer than
the b-chain and contents 1 or more cysteins which form the disulphide bridge in
the F(ab')2-fragment generated by pepsin cleavage. The b- and b'-notation is
used to differentiate between antibody fragments generated by Papain and Pepsin
cleavage.
Hope this helps, Marcus
Marcus Macht
Faculty of Chemistry
Analytical Chemistry
University of Constance
Germany