the substitution of hydroxyproline for proline in position y of the repeating gly-x-y tripeptide sequence of collagen-like poly ( tripeptide ) s ( i.e. , in the position in which hyp occurs naturally ) is predicted to enhance the stability of aggregates of triple helices , while the substitution of hyp in position x ( where no hyp occurs naturally ) is predicted to decrease the stability of aggregates .
C0020388
hydroxyproline
C0033382
proline