MIMM 214 Lecture Notes - Lecture 25: Immunoglobulin G, Helminths, Monomer
7 Jun 2018
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Lecture 26 – March 10, 2017
Antibody Structure
Structure of an immunoglobin
- Y shaped glycoprotein
- Made up of 2 identical disulfide bond linked heavy (H) chains and 2 identical light (L) chains
- Each chain uses Ig like domains
- 4 chains in total
- Variable regions
o Both the heavy and light chain have a variable region
- Constant regions
o Both the heavy and light chain have a constant region
- Variable regions function: Ag binding
o VL and VH forms antigen-binding site (2 identical sites per antibody)
o Binding can result in neutralization
▪ i.e. toxins or virus
- Constant regions function: effector function:
o Complement activation
o Constant region (Fc) can bind to Fc receptors on phagocytes and other cell types (eg
mast cells, eosinophils)
Cleavage by Papain
- Papain
o Cleaves antibody near the disulphide bonds that connect the two heavy chains
o Cleaves Ab into 3 molecules
- Fab fragments
o Two Fab fragments pre antibody
o Each has antigen-binding binding domain AND part of the constant H and L chains
o Fab = fragment antigen binding
- Fc fragments
o One Fc fragment
o Fc = fragment crystalizable
o Receptors that bind antibodies recognize the Fc region
Immunoglobulin = Antibody
- Two heavy chains (variable and constant regions)
- Two light chains (variable and constant regions)
- Held together by intra/inter-chain disulfide covalent bonds
Question
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Made up of 2 identical disulfide bond linked heavy (h) chains and 2 identical light (l) chains. Variable regions: both the heavy and light chain have a variable region. Constant regions: both the heavy and light chain have a constant region. Variable regions function: ag binding: vl and vh forms antigen-binding site (2 identical sites per antibody, binding can result in neutralization i. e. toxins or virus. Constant regions function: effector function: complement activation, constant region (fc) can bind to fc receptors on phagocytes and other cell types (eg mast cells, eosinophils) Papain: cleaves antibody near the disulphide bonds that connect the two heavy chains, cleaves ab into 3 molecules. Fab fragments: two fab fragments pre antibody, each has antigen-binding binding domain and part of the constant h and l chains, fab = fragment antigen binding. Fc fragments: one fc fragment, fc = fragment crystalizable, receptors that bind antibodies recognize the fc region. Held together by intra/inter-chain disulfide covalent bonds.
