Ionic bond strength in protein folding?

[stratz]

Our text says that ionic bonds are much weaker in aqueous solutions than covalent bonds, due to the dissociative properties of most ionic compounds in water. I read elsewhere though, that in general, ionic bonds are stronger due to the increased polarity.

So, in protein folding, when different chains interact, would a lot of polar bonds in the side chains of amino acids result in a tighter, more compact protein structure, or a looser structure?

 

[Comeback City]

Our text says that ionic bonds are much weaker in aqueous solutions than covalent bonds, due to the dissociative properties of most ionic compounds in water. I read elsewhere though, that in general, ionic bonds are stronger due to the increased polarity.

So, in protein folding, when different chains interact, would a lot of polar bonds in the side chains of amino acids result in a tighter, more compact protein structure, or a looser structure?

Ionic bonds are still stronger when not dissolved in water, so I think they would be stronger than polar covalent bonds in protein folding.

 

[Ygggdrasil]

Because proteins exist in aqueous environments, ionic bonds in proteins are fairly weak and transient compared to covalent bonds. What ends up providing a lot of the driving force for protein folding and protein-protein interactions is the hydrophobic effect. In general, hydrophobic side chains of proteins will tend to associate together inside of the interior of proteins where as polar side chains, which can be solvated by water, are on the outside. Some regions of proteins with many polar and charged side chains are intrinsically unstructured, which probably makes them less compact than the typical globular regions of proteins.