17152
Finally , MD simulations of aggregation - prone A beta heptapeptide segments show that carnosine reduces the propensity to form intermolecular backbone hydrogen bonds in the region 18 - 24 .
 Chemical: heptapeptide; Chemical: carnosine; Chemical: hydrogen
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: heptapeptide; Chemical: carnosine; Chemical: hydrogen