Lecture 5 : Antibody binding Flashcards
What makes GFP (jellyfish protein) so stable
Beta barrel structure.
What is an antibody/ immunoglobulin
Function is to bind to foreign molecules (antigen) with selectivity and affinity to neutralise them.
Compare domains and Quaternary/oligomeric structure
Domains are separately folded regions of the same proteins whereas Quaternary/oligomeric structure is where 2 or more different polypeptide chains interact together by weak interactions to form a functional unit. Oligomer = many units
Why do Proteins have different domains (4 reasons)
- Smaller units lead to more efficient folding for proteins with a lot of chains as less mistakes/ shorter time
- Active sites can be made between the clefts between domains
- This allows different domains to undergo different activities
- This allows flexibility which is important for domains to close over the bound substrate
Compare the domains and quaternary structure of IgG antibody
It is a tetramer with 2 heavy chains and 2 light chains in a Y shape. The heavy chains have 4 domains on them while the light chains have 2 domains on them.
The domains allow flexible hinges between the two arms and binding site cleft on the end of the two light chains
Describe the structural features that allow antibody to be very selective
-Each variable domain of the light chain arms has 3 hypervariable loops= 6 loops in total per site. As there are 2 arms there are 2 identical binding sites per antibody
Describe the structural feature that allows antibodies to increase the strength of their binding
The domain structure with links inbetween allows flexibility which means that a single antibody can bind to two antigens at the same time with an adjustable distance and this increases binding affinity
What are the factors that determine molecular recognition
- shape - bulging, narrow
- size
- charge (opposites attract)
- polar/non polar character for H bonding
- van der waals interactions
