20530
IPNS thus converts the homologated tripeptides delta - ( L - alpha - aminoadipoyl ) - L - homocysteinyl - D - valine ( AhCV ) and delta - ( L - alpha - aminoadipoyl ) - L - homocysteinyl - D - allylglycine ( AhCaG ) into monocyclic hydroxy - lactam products ; this suggests that the additional methylene unit in these substrates induces conformational changes that preclude second ring closure after initial lactam formation .
 delta - ( L - alpha - aminoadipoyl ) - L - homocysteinyl - D - valine, AhCV, delta - ( L - alpha - aminoadipoyl ) - L - homocysteinyl - D - allylglycine, AhCaG, monocyclic hydroxy - lactam, methylene, lactam
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 delta - ( L - alpha - aminoadipoyl ) - L - homocysteinyl - D - valine, AhCV, delta - ( L - alpha - aminoadipoyl ) - L - homocysteinyl - D - allylglycine, AhCaG, monocyclic hydroxy - lactam, methylene, lactam