What type of bond is directly involved in the formation of an α-helix? a. peptide bonds between amino acid residues b. hydrogen bonds between amino acid residues c. van der Waals interactions between nonpolar residues d. disulfide bonds between cysteine residues

Verified step by step guidance

1. Identify the structure in question: An α-helix is a common secondary structure in proteins, characterized by a right-handed coiled or spiral shape.
2. Recall the types of bonds in protein structures: Proteins have several types of bonds, including peptide bonds, hydrogen bonds, van der Waals interactions, and disulfide bonds.
3. Understand the role of peptide bonds: Peptide bonds are the primary chemical bonds that link amino acids together into a polypeptide chain, forming the primary structure of proteins.
4. Recognize the role of hydrogen bonds in α-helices: In an α-helix, hydrogen bonds form between the carbonyl oxygen of one amino acid residue and the amide hydrogen of another amino acid residue, which is typically four residues away. This bonding pattern helps to stabilize the helical structure.
5. Conclude the correct answer: The type of bond directly involved in the formation of an α-helix is hydrogen bonds between amino acid residues.

Key Concepts

Peptide Bonds

Peptide bonds are covalent bonds that link amino acids together in a protein. They form through a dehydration reaction between the carboxyl group of one amino acid and the amino group of another, resulting in a chain of amino acids known as a polypeptide. While essential for protein structure, peptide bonds do not directly stabilize secondary structures like the α-helix.

Hydrogen Bonds

Hydrogen bonds are weak attractions that occur between a hydrogen atom covalently bonded to an electronegative atom and another electronegative atom. In the context of an α-helix, hydrogen bonds form between the carbonyl oxygen of one amino acid and the amide hydrogen of another, stabilizing the helical structure. This interaction is crucial for maintaining the secondary structure of proteins.

Secondary Structure

Secondary structure refers to the local folded structures that form within a protein due to interactions between the backbone atoms. Common types include α-helices and β-pleated sheets, which are stabilized by hydrogen bonds. Understanding secondary structure is vital for grasping how proteins achieve their functional shapes and how these shapes relate to their biological roles.