Final answer:
Protein chains intertwine to form a coiled structure known as the alpha-helix or beta-pleated sheet.
Step-by-step explanation:
The polypeptide chains intertwine around each other to create the spiral shape of a coiled protein. These chains form secondary structures such as the alpha-helix and beta-pleated sheet. The alpha-helix is a right-handed spiral held together by hydrogen bonds between the carbonyl and amide groups of the amino acids. The beta-pleated sheet is a pleated structure formed by hydrogen bonds between adjacent polypeptide chains.