1. Loop regions are at the surface of protein molecules.

2. In general, C=O and NH of loops do not form H-bonds to each other. And they exposed to the solvent and can form H-bonds to water molecules.

3. Rich in charged and polar(hydrophilic) residues.

4.Unstable.(invisible in x-ray structures)

5. Binding sites.

6. Hairpin loops(reverse turns).