3.2 Disulfide Bridges

Disulfide Bridges (Module 3: The Architect). Key concept: Covalent cross-links. Explain how a disulfide differs from every other stabilising interaction by being covalent.

• Explain how a disulfide differs from every other stabilising interaction by being covalent
• Apply the geometric requirements: Cα–Cα roughly 4.5–6.5 Å, with a C–S–S–C dihedral near ±90°
• Explain why disulfides matter most for proteins that leave the reducing cytoplasm
• Recognise that two cysteines in a structure do not make a disulfide