Threonine and asparagine are polar (hydrophillic-water loving)
amino acids. They interact with one another by side-chain hydrogen
bonding. This interaction in likely to form on the surface of a
protein. Polar amino acids are usually found exposed on the surface
of a protein since their side-chains prefer to reside in an aqueous
environment.
H-bonds have been found to make a positive contribution to
protein stabilization. Polar amino acids are hydrogen bonded to
each other or to water molecules. Water molecules are also involved
in the stabilization of the protein structure since they make
hydrogen bonds with the main chain and side-chain groups.
