In my view turns firstly serve the structural role of redirecting the polypeptide chain towards the protein core, or to the more globular region anyway. Obviously, without turns a protein could not be globular. They are also regions of strong sequence selection; beta-turns follow specific stereochemical rules that can be obeyed mostly by only few amino acid sequences (see Gly-turn, Pro-turn, ...); this should also apply to gamma-turns, for which I have a limited statistics. Turns can serve a recognition purpose, being among the parts of the proten moiety that are most visible to extrenal binders. I am less sure about their role during folding, but would not be surprised if they played a key role, at least as easily foldable elements.

Thank you for the answer. However, would these turns be implied in protein-protein interactions?

They may indeed, but You cannot make a general statement .

Thanks