15644
By using ultrafiltration , gel filtration chromatography and reversed phase high performance liquid chromatography ( RP - HPLC ) , a novel antioxidant peptide ( BNH - P7 ) was isolated from BNH , and its amino acid sequence was identified as YPPAK ( Tyr - Pro - Pro - Ala - Lys ) with molecular weight of 574 Da .
 Chemical: amino acid; Chemical: Tyr - Pro - Pro - Ala - Lys
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: amino acid; Chemical: Tyr - Pro - Pro - Ala - Lys