7390
These enzymes convert proline residues within the repeat regions of collagen polypeptides to 4 - hydroxyproline , a modification essential for the stability of the final triple helix .
 Chemical: proline; Chemical: 4 - hydroxyproline
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: proline; Chemical: 4 - hydroxyproline