# 1.4 The Special Characters

> The Special Characters (Module 1: The Building Blocks). Key concept: Proline, glycine, cysteine. Explain why proline breaks helices and favours turns.

The Special Characters (Module 1: The Building Blocks). Key concept: Proline, glycine, cysteine. Explain why proline breaks helices and favours turns.

- Explain why proline breaks helices and favours turns
- Explain why glycine allows backbone geometry no other residue can reach
- Explain how a disulfide bond forms and why it stabilises a fold
- Predict what placing one of these three residues in the wrong context would do

## Links

- [Module 1: The Building Blocks](https://proteindesign.academy/module/1)
- [Introduction](https://proteindesign.academy/module/1/intro)
- [1.1 The Hydrophobic Effect](https://proteindesign.academy/module/1/1)
- [1.2 Electrostatics & Salt Bridges](https://proteindesign.academy/module/1/2)
- [1.3 Size & Shape: The Packing Game](https://proteindesign.academy/module/1/3)
- [1.5 Aromatic Interactions](https://proteindesign.academy/module/1/5)
- [The Peptide Engineer](https://proteindesign.academy/module/1/capstone)