the dipeptides were identified as r-proline and r'-hydroxyproline where r is any one of the residues , glycyl , alanyl , valyl , leucyl , isoleucyl , seryl , aspartyl , glutamyl , prolyl , phenylalanyl and r ' is alanyl , valyl , leucyl or isoleucyl , seryl , prolyl , glutamyl , phenylalanyl .
C0033382
proline
C0020388
hydroxyproline