You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule 4-amino-2-[(2-amino-3-methylbutanoyl)-[2-(cyclohexylamino)acetyl]amino]-2-(2-methylsulfanylethyl)-3-oxo-5-sulfanylpentanoic acid .
user
C21H38N4O5S2
assistant