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- Fragmentation of Immunoglobulin Molecules
- OSF - 8
- Pages 108 & 109
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- History:
- e1962 - Rodney Porter proposed the basic structure of the immunoglobulin
molecule
- eUsed proteolytic enzymes to cleave rabitt IgG
- eThese proteolytic enzymes were:
- ˇpapain
- ˇpepsin
- eThe results of treatment with these enzymes was the production of
different fragments of the IgG molecule
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- Fragmentation with Papain:
- cleaves molecule at hinge region
- 2 FAB fragments
- 1 Fc fragment
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- Fragmentation with Pepsin:
- cleaves molecule below hinge region
- 1 FAB fragment
- 2 Fc fragments
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- Outcomes from fragmentation experiments:
- eall basic Ig molecules (monomeric forms) have 2 separate
antigen-binding sites (FAB) each containing VL and VH
pair
- eeach VL - VH pair serves as an independent
antigen- binding site
- ethe secreted form of IgM contains five monomeric units - thus 10
separate antigen-binding sites
- ethe hinge region of an Ig molecule provides flexibility which
determines how many of the ab=s antigen-binding sites will bind with
epitopes on antigens
- ethe location and functions of the Fc portion of the Ig are separate
from that of the FAB region
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- Outcomes from fragmentation experiments: continued
- ebiological functions that are activated by Fc regions during the immune
response are not antigen specific
- ebiological functions that are activated by Fc regions during the immune
response are Ig class-specific
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Notes
