6JYM:
reference: Characterization and crystal structure of prolyl endopeptidase from abalone (Haliotis discus hannai)., Li WY, Li Y, Chen YL, Hu JJ, Mengist HM, Liu GM, Jin T, Cao MJ, Food Chem. 2020 Dec 15;333:127452. doi: 10.1016/j.foodchem.2020.127452. Epub 2020, Jul 4. PMID: 32673951

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