Medicine & USMLE

Tertiary Structure

Protein Structure
  1. Primary Protein Structure
  2. Secondary Protein Structure
  3. Tertiary Structure
  4. Quaternary Protein Structure


Tertiary structure describes the 3-dimensional structure of a protein, as dictated by side-chain interactions and interactions with water. Specific types of side-chain interactions include hydrogen bonding, electrostatic interactions, and disulfide bonding.

Key Points

  • Tertiary Structure
    • interactions between side chains (R-groups) and folding in water
      • Normally, distant residues interacting (occurs when several secondary structures come together)
      • note - NOT PEPTIDE BACKBONE (contrast vs secondary)
    • Primary driving force is hydrophilic and hydrophobic interactions
      • Non-polar groups face the interior of the protein, polar groups face the exterior of the protein 
    • But also includes
      • Hydrogen bonding
      • Electrostatic attraction (ionic/salt bridge)
      • Van der Waals forces
      • Disulfide bonds (type of covalent bond)