title: Isolation of prolyl endopeptidase inhibitory peptides from a sodium caseinate hydrolysate.
abstract: Prolyl endopeptidase (PEP) has been associated with neurodegenerative disorders, and the PEP inhibitors can restore the memory loss caused by amnesic compounds. In this study, we investigated the PEP inhibitory activity of the enzymatic hydrolysates from various food protein sources, and isolated and identified the PEP inhibitory peptides. The hydrolysate obtained from sodium caseinate using bromelain (SC/BML) displayed the highest inhibitory activity of 86.8% at 5 mg mL(-1) in the present study, and its IC50 value against PEP was 0.77 mg mL(-1). The F-5 fraction by RP-HPLC (reversed-phase high performance liquid chromatography) from SC/BML showed the highest PEP inhibition rate of 88.4%, and 9 peptide sequences were identified. The synthetic peptides (1245.63-1787.94 Da) showed dose-dependent inhibition effects on PEP as competitive inhibitors with IC50 values between 29.8 and 650.5 μM. The results suggest that the peptides derived from sodium caseinate have the potential to be PEP inhibitors.
authors.affiliation: Department of Health Nutrition and Biotechnology, Asia University, 500 Lioufeng Road, Wufeng, Taichung 41354, Taiwan. kchsu@mail.cmu.edu.tw.
authors.forename: Cheng-Hong
authors.initials: CH
authors.lastname: Hsieh
authors.affiliation: Division of Endocrine and Metabolism, China Medical University Hospital, 2 Yude Road, Taichung, 40447, Taiwan.
authors.forename: Tzu-Yuan
authors.initials: TY
authors.lastname: Wang
authors.affiliation: Food Safety and Inspection Center, Asia University, 500 Lioufeng Road, Wufeng, Taichung 41354, Taiwan and Department of Nutrition, China Medical University, 91 Hsueh-Shih Road, Taichung 40402, Taiwan.
authors.forename: Chuan-Chuan
authors.initials: CC
authors.lastname: Hung
authors.affiliation: Department of Health Nutrition and Biotechnology, Asia University, 500 Lioufeng Road, Wufeng, Taichung 41354, Taiwan. kchsu@mail.cmu.edu.tw.
authors.forename: You-Liang
authors.initials: YL
authors.lastname: Hsieh
authors.affiliation: Department of Health Nutrition and Biotechnology, Asia University, 500 Lioufeng Road, Wufeng, Taichung 41354, Taiwan. kchsu@mail.cmu.edu.tw and Food Safety and Inspection Center, Asia University, 500 Lioufeng Road, Wufeng, Taichung 41354, Taiwan.
authors.forename: Kuo-Chiang
authors.initials: KC
authors.lastname: Hsu
mesh_terms: D000595:Amino Acid Sequence; D002364:Caseins / Q000737:chemistry*; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D006868:Hydrolysis; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology*; D000085822:Prolyl Oligopeptidases; D012697:Serine Endopeptidases / Q000378:metabolism*
chemical_list: D002364:Caseins; D004791:Enzyme Inhibitors; D010455:Peptides; D012697:Serine Endopeptidases; D000085822:Prolyl Oligopeptidases