Question

Match the following conformations of proteins with their specific types of bonds that stabilises them.

• A. H-bonds
• B. Peptide bonds
• C. Disulfide bonds

Answer 1

The structures of proteins are described in four levels:

1. Primary structure - is formed by amino acids held together by peptide bond. The simple polypeptide chain forms the primary structure.
2. Secondary structure: Two polypeptide chains held together by H-bonds form a secondary structure.
3. Tertiary structure: Side chains of the amino acids constituting the secondary structure form ionic bonds or covalent disulfide bridges with the side chains of the other amino acids in the secondary structure. This results in further folding of the proteins, forming a tertiary structure.
4. Quaternary structure: A single tertiary structure may be a single subunit of a protein. Such multiple subunits are bound together to each other to form a functional protein and this structure is called a quarternary structure. Most of the bonds stabilising tertiary structure also stabilises the quarternary structure.