6BBB0333
L7 – Engineering Antibody Alternatives
Introduction
- Antibodies fulfil numerous roles both in biology - as evolution intended - as well as in
research, medicine and general biotech applications (e.g. measuring protein concentration in
ELISA)
- For a multitude of reasons the search for alternatives is going on for some time leading to an
interesting group of molecules.
- One of the most recent and most promising examples is a group of proteins called ‘Adhirons’
or ‘Affimers’ that tick many boxes expected for such replacements which could make them
very interesting in the future.
- They are a fairly recent development with the first publication from 2014.
An affirmer
- Beta-alpha mixed protein
- 4 beta strands wrapping around a long alpha helix
- Very compact, stable fold (important for design)
Antibody types
- Most popular IgG – used a lot in biotech
- Building blocks are heavy and light chains
, 6BBB0333
o Based on beta sandwich structures
- Combined in a myriad of ways – small IgG, dimerised IgA (additional protein to make dimer),
IgE (extension of constant heavy chain – 3 instead of 2), IgM (5 – can bind 5 antigens in one
go)
Antibody architecture
- Light chains
o Two immunoglobulin-type beta sandwich domains
- Heavy chain (twice the size of LC) – possibly an evolutionary gene duplication event between
the two different chains
- Heavy chain has constant and variable region
- Variable region is very first domain of either heavy or light chain
- It is responsible for antigen binding (occurs at tip of whole structure)
- Very small potion of whole protein is interacting with antigen
o Large size is downside of proteins
- In the native environment (IS) it makes sense to have a large protein:
o While one portion is relevant for antigen binding (tip)…
o the other portion (effector region) is responsible for binding to antigen receptor on
immune cells
o Combination of this triggers immune response so both parts are essential BUT
- If you want to use antibodies outside of cellular/physiological context, this extra (bottom)
portion is not necessary and we can do away with it
L7 – Engineering Antibody Alternatives
Introduction
- Antibodies fulfil numerous roles both in biology - as evolution intended - as well as in
research, medicine and general biotech applications (e.g. measuring protein concentration in
ELISA)
- For a multitude of reasons the search for alternatives is going on for some time leading to an
interesting group of molecules.
- One of the most recent and most promising examples is a group of proteins called ‘Adhirons’
or ‘Affimers’ that tick many boxes expected for such replacements which could make them
very interesting in the future.
- They are a fairly recent development with the first publication from 2014.
An affirmer
- Beta-alpha mixed protein
- 4 beta strands wrapping around a long alpha helix
- Very compact, stable fold (important for design)
Antibody types
- Most popular IgG – used a lot in biotech
- Building blocks are heavy and light chains
, 6BBB0333
o Based on beta sandwich structures
- Combined in a myriad of ways – small IgG, dimerised IgA (additional protein to make dimer),
IgE (extension of constant heavy chain – 3 instead of 2), IgM (5 – can bind 5 antigens in one
go)
Antibody architecture
- Light chains
o Two immunoglobulin-type beta sandwich domains
- Heavy chain (twice the size of LC) – possibly an evolutionary gene duplication event between
the two different chains
- Heavy chain has constant and variable region
- Variable region is very first domain of either heavy or light chain
- It is responsible for antigen binding (occurs at tip of whole structure)
- Very small potion of whole protein is interacting with antigen
o Large size is downside of proteins
- In the native environment (IS) it makes sense to have a large protein:
o While one portion is relevant for antigen binding (tip)…
o the other portion (effector region) is responsible for binding to antigen receptor on
immune cells
o Combination of this triggers immune response so both parts are essential BUT
- If you want to use antibodies outside of cellular/physiological context, this extra (bottom)
portion is not necessary and we can do away with it
