Category: amino-acid
Aliases: Pro, P, L-Proline
Only cyclic amino acid (side chain links back to α-amino N). Disrupts α-helical secondary structure ('helix-breaker'); enables kinks + turns. Hydroxyproline (from prolyl-4-hydroxylase, vitamin-C-dependent) is critical to the collagen triple helix — ~25% of collagen residues are Pro/Hyp.