7121
Finally , our comparative sequence analyses revealed that the residues equivalent to Asp121 and Phe170 are highly conserved in many ALDH families irrespective of their substrate specificity - suggesting that they perform a role in catalysis additional or different to binding of the substrate - and that the positions Met124 , Cys301 , and Cys303 are hot spots changed during evolution to confer aldehyde specificity to several ALDH families .
 Chemical: Asp121; Chemical: Phe170; Chemical: Met124; Chemical: Cys301; Chemical: Cys303; Chemical: aldehyde
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: Asp121; Chemical: Phe170; Chemical: Met124; Chemical: Cys301; Chemical: Cys303; Chemical: aldehyde