title: Peptide identification and angiotensin converting enzyme (ACE) inhibitory activity in prolyl endoproteinase digests of bovine α(s)-casein.
abstract: Incubation of sodium caseinate (NaCN) and purified α-casein (αs-CN) with an Aspergillus niger derived prolyl endoproteinase (An-PEP) for 1, 2, 3, 4, 8 and 24 h resulted in the generation of potent angiotensin converting enzyme (ACE) inhibitory hydrolysates. An ACE IC50 of 21.1±5.1 μg/ml was obtained on incubation of An-PEP with NaCN for 4 h. Fractionation of the NaCN hydrolysates using 3 kDa centrifugal filters resulted in highly active permeate fractions, the most potent being obtained from the 3 h hydrolysate (ACE IC50=2.9±0.3 μg/ml). The hydrolytic specificity of An-PEP for purified α-CN was assessed using UPLC ESI MS/MS. The analysis confirmed An-PEP's cleavage preference for the C-terminal side of Pro and also confirmed that An-PEP has the ability to cleave at the C-terminal of Ala, Leu, Arg and His residues.
authors.affiliation: Department of Life Sciences, University of Limerick, Ireland.
authors.forename: Roseanne
authors.initials: R
authors.lastname: Norris
authors.affiliation: Department of Life Sciences, University of Limerick, Ireland.
authors.forename: Martina B
authors.initials: MB
authors.lastname: O'Keeffe
authors.affiliation: Department of Life Sciences, University of Limerick, Ireland; Food for Health Ireland, University of Limerick, Ireland.
authors.forename: Alexey
authors.initials: A
authors.lastname: Poyarkov
authors.affiliation: Department of Life Sciences, University of Limerick, Ireland; Food for Health Ireland, University of Limerick, Ireland. Electronic address: dick.fitzgerald@ul.ie.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: FitzGerald
mesh_terms: D000806:Angiotensin-Converting Enzyme Inhibitors; D000818:Animals; D001234:Aspergillus niger / Q000201:enzymology; D002364:Caseins / Q000737:chemistry* / Q000378:metabolism; D002417:Cattle; D005591:Chemical Fractionation; D006868:Hydrolysis; D010455:Peptides / Q000032:analysis* / Q000494:pharmacology; D000085822:Prolyl Oligopeptidases; D012697:Serine Endopeptidases / Q000378:metabolism*; D053719:Tandem Mass Spectrometry
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D002364:Caseins; D010455:Peptides; D012697:Serine Endopeptidases; D000085822:Prolyl Oligopeptidases
keywords: ACE inhibition; Aspergillus niger derived prolyl endoproteinase; LC–MS; Simulated gastrointestinal digestion; Sodium caseinate; Substrate specificity; α-Casein