the procollagen peptide consists of three segments , an n-terminal globular domain which contains all the cysteine residues and most of the hydrophobic residues present in the entire peptide , a triple helical part with a relatively high content of proline and hydroxyproline , and a short nonhelical region which forms the connection to the nonhelical region of the alpha 1 ( i ) chain and which contains the proline-glutamine bond specifically split by the n-terminal procollagen peptidase during conversion of procollagen to collagen .
C0020388
hydroxyproline
C0033382
proline