Question

A-helix supercoiling: nonpolar side chains along each a-helix can be arranged so that their side groups can ________?

1) interact with each other
2) form hydrogen bonds
3) bind to polar side chains
4) rotate freely

Answer 1

The nonpolar side chains along each alpha-helix in proteins can interact with each other through hydrophobic interactions, contributing to the stability of the protein's tertiary structure.

Step-by-step explanation:

The nonpolar side chains along each alpha-helix in a protein structure can interact with each other through hydrophobic interactions. In the alpha-helix structure, the polypeptide chain forms a right-handed coil with the nonpolar side chains sticking out and often found in the interior of the protein, where they can avoid water and stabilize the protein's tertiary structure by interacting with other hydrophobic side chains. These interactions are typically van der Waals forces rather than hydrogen bonds, as hydrogen bonds are mainly formed within the peptide backbone to maintain the alpha-helix's secondary structure. Additionally, disulfide linkages, the only covalent bonds formed during protein folding, can occur between cysteine residues, further contributing to the stability of the protein structure.