Antibody structure & function Flashcards
What can the heavy chain consist of?
Alpha, delta, epsilon, gamma, mu
What can the light chain consist of?
Lambda, and K
How did they assign biological function to structure?
Proteolytic cleavage
Pepsin digestion of Ig
F(ab’)2 and Fc fragments
Papain digestion of Ig
2 x Fab and Fc
Mercaptoethanol reduction
H chains and L chains
What do the VL and VH domains contain?
3 hypervariable (CDR) regions
Which chain determines what kind of antibody you have?
Heavy chain
What defines the specificity of antibodies?
VH and VL regions
How is the antigen binding site created?
CDRs pf H and L chains combine
Types of antigen epitopes
Multivalent antigen with different epitopes, multivalent antigen with repeated epitope, linear epitope or discontinuous epitope
Polyclonal
Antibodies secreted by different B cell lineages e.g. serum antibodies
How are monoclonal antibodies derived?
From a single plasma cell
What can monoclonal antibodies be used for?
Treating disease
What are the 4 types of therapeutic monoclonal antibody?
Mouse, chimeric, humanised, human
What are the IgG subclasses?
IgG1, IgG2, IgG3, IgG4
How do the IgG subclasses differ?
Arrangement of disulphide bonds linking the heavy chains
Which IgG subclass is most susceptible to proteolytic cleavage but has greater capacity to bind C1q and activate complement
IgG3
What antibodies are good at activating and fixing complement
IgM and IgG3
What is the first complement
C1q (consists of 18 peptide chains)
What antibodies are bad at activating and fixing complement?
IgD, IgG4, IgE
What does IgM contain that is required for polymerisation?
J chain
How many antigen binding sites does IgM contain?
10
What is IgA important for?
External secretions (mucosal surfaces e.g. gut, lungs)
