21650
We have constructed a novel class of " double - hydrophobic " block polypeptides based on the hydrophobic domains found in native elastin , an extracellular matrix protein responsible for the elasticity and resilience of tissues .
 None
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 None