Amino acids may be either polar or non-polar depending on the composition of their side chain
- Polar amino acids have hydrophilic R groups, while non-polar amino acids have hydrophobic R groups
The localisation of polar and non-polar amino acids will be determined by the type of protein and its function:
Water soluble proteins:
- Non-polar amino acids tend to be found in the centre of the molecule (stabilise the structure)
- Polar amino acids tend to be located on the protein surface (capable of interacting with water molecules)
Membrane-bound proteins:
- Non-polar amino acids tend to be located on the regions of the surface in contact with the membrane
- Polar amino acids will generally line interior pores (to create hydrophilic channels)
Enzymes:
- The active site specifically depends on the location and distribution of polar and non-polar amino acids as hydrophobic and hydrophilic interactions can play a role in substrate binding to the active site
Polar versus Non-Polar Amino Acids
