15174
Here , the role of the three proline residues ( Pro ( 2 ) , Pro ( 3 ) , and Pro ( 7 ) ) in establishing these conformations is investigated using a series of seven analogue peptides in which combinations of alanine residues are substituted for prolines .
 Chemical: proline; Chemical: Pro; Chemical: Pro; Chemical: Pro; Chemical: alanine; Chemical: prolines
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: Pro; Chemical: Pro; Chemical: Pro; Chemical: alanine; Chemical: prolines