Salt-Bridges in the Microenvironment of Stable Protein Structures

Abstract

Salt-bridges (sb) play an important role in the folding and stability of proteins. This is deduced from the evaluation of net energy in the microenvironments (ME, residues that are 4Å away from positive and negative partners of salt-bridge and interact with them). ME’s act as a determinant of net-energy due to the intrinsic features by the sequence. The stability of extremophilic proteins is due to the presence of favorable residues at the ME without any unfavorable residues. We studied a dataset of four structures from the pdb and a homology model (PDB ID: 1HM5) to gain insights on this issue. Data shows that the presence of isolated charges and polar residues in the core of extremophilic proteins helps in the formation of stable salt-bridges with reduced desolvation. Thus, site-specific mutations with favorable residues at the ME will help develop thermo stable proteins with strong salt bridges.