Fragmentation of Immunoglobulins

The success of Porter was fortuitous in that it provided a method of easily dividing the molecule into its two msyor functional parts. This led many investigators to examine the effect of other enzymes on immunoglobulins with the hope of further localizing these functions more precisely. 

The mouse IgA myeloma 315, which has antibodylike activity for the 2,4-dinitrophenyl (DNP) group, on treatment with pepsin at pH 3.8 

Another point evident from these studies is that there is little non-covalent interaction between domains on the same polypeptide chain since simple proteolysis causes their separation. This is in contrast to the domains that are aligned with each other or paired in the native molecule, such as the Vh and Vl domains or the Ch3 domains on separate H chains. 

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Representations in a stylised diagrammatic form of three proteins (interleukin-l/J, zinc insulin dimers, and the Fc fragment of immunoglobulin) are shown in Fig. 11.3. The nature of the three-dimensional stmcture shows how difficult it is to define proteins in conventional ways, and how they must be considered in a new light as pharmaceutical... 

Figure 11.3 Ribbon diagrams of (a) interleukin 1-/ , (b) zinc-insulin dimer and (c) the Fc fragment of immunoglobulin.

McClurkan M B et al. (1993). Disposition of a monoclonal anti-phencyclidine Fab fragment of immunoglobulin G in rats. J. Pharmacol. Experim. Therapeu. 266 1439-1445. 

Marine anti-[high a-(13)-content dextran] antibody production by hybrid cells has been reported. Binding studies of methyl 6-(9-benzoyl- 3-D-galacto-pyranoside to the Fab fragment of immunoglobulin J539 have indicated that the phenyl group appears to participate in interactions with the antibody. ... 

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