title: Angiotensin I-converting enzyme inhibitory properties of whey protein digests: concentration and characterization of active peptides.
abstract: The aim of this study was to identify whey-derived peptides with angiotensin I-converting enzyme (ACE) inhibitory activity. The bovine whey proteins alpha-lactalbumin and beta-lactoglobulin were hydrolysed with pepsin, trypsin, chymotrypsin, pancreatin, elastase or carboxypeptidase alone and in combination. The total hydrolysates were fractionated in a two step ultrafiltration process, first with a 30 kDa membrane and then with a 1 kDa membrane. Inhibition of ACE was analysed spectrophotometrically. The peptides were isolated by chromatography and identified by mass and sequencing analysis. The most potent inhibitory peptides were synthesized by the 9-fluorenylmethoxycarbonyl solid phase method. Inhibition of ACE was observed after hydrolysis with trypsin alone, and with an enzyme combination containing pepsin, trypsin and chymotrypsin. Whey protein digests gave a 50% inhibition (IC50) of ACE activity at concentration ranges within 345-1733 micrograms/ml. The IC50 values for the 1-30 kDa fractions ranged from 485 to 1134 micrograms/ml and for the < 1 kDa fraction from 109 to 837 mg/ml. Several ACE-inhibitory peptides were isolated from the hydrolysates by reversed-phase chromatography, and the potencies of the purified peptide fractions had IC50 values of 77-1062 microM. The ACE-inhibitory peptides identified were alpha-lactalbumin fractions (50-52), (99-108) and (104-108) and beta-lactoglobulin fractions (22-25), (32-40), (81-83), (94-100), (106-111) and (142-146).
authors.affiliation: Agricultural Research Centre of Finland, Jokioinen, Finland.
authors.forename: A
authors.initials: A
authors.lastname: Pihlanto-Leppälä
authors.forename: P
authors.initials: P
authors.lastname: Koskinen
authors.forename: K
authors.initials: K
authors.lastname: Piilola
authors.forename: T
authors.initials: T
authors.lastname: Tupasela
authors.forename: H
authors.initials: H
authors.lastname: Korhonen
mesh_terms: D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology*; D000818:Animals; D002268:Carboxypeptidases / Q000378:metabolism; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D002918:Chymotrypsin / Q000378:metabolism; D006868:Hydrolysis; D007768:Lactalbumin / Q000737:chemistry / Q000378:metabolism; D007782:Lactoglobulins / Q000737:chemistry / Q000378:metabolism; D008894:Milk Proteins / Q000378:metabolism*; D010196:Pancreatic Elastase / Q000378:metabolism; D010194:Pancreatin / Q000378:metabolism; D010434:Pepsin A / Q000378:metabolism; D010446:Peptide Fragments / Q000302:isolation & purification / Q000494:pharmacology*; D014357:Trypsin / Q000378:metabolism; D000067816:Whey Proteins
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D007782:Lactoglobulins; D008894:Milk Proteins; D010446:Peptide Fragments; D000067816:Whey Proteins; D010194:Pancreatin; D007768:Lactalbumin; D002268:Carboxypeptidases; D002918:Chymotrypsin; D010196:Pancreatic Elastase; D014357:Trypsin; D010434:Pepsin A