Question

What protein characteristics are necessary for high salt tolerance? Does this principle apply to low-salt environments? Why or why not?

Answer 1

The proteins that have the capability for high salt-tolerance are usually halophilic proteins found in halophilic bacteria that are known to withstand extremely high-salt concentrations. These proteins are highly acidic in nature i.e, they contain numerous negatively charged amino acid residues. This property imparts hydrophilicity to the protein. At high-salt concentrations, this property ensures better solubility and reversible folding of the protein.

This principle however does not apply for low-salt environments since halophilic proteins are designed to be stable at high-salt environments. At low-salt conditions, low concentrations of solutes fail to mask the highly acidic surface of the halophilic proteins which leads to the disruption of the native stable conformation of these proteins.