7231
We show that , in contrast to long chain unsaturated substrates , the rate - limiting step of retinal oxidation by RALDHs is associated with acylation .
 Chemical: retinal
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: retinal