title: Degradation and debittering of a tryptic digest from beta-casein by aminopeptidase N from Lactococcus lactis subsp. cremoris Wg2.
abstract: The mode of action of purified aminopeptidase N from Lactococcus lactis subsp. cremoris Wg2 on a complex peptide mixture of a tryptic digest from bovine beta-casein was analyzed. The oligopeptides produced in the tryptic digest before and after aminopeptidase N treatment were identified by analysis of the N- and C-terminal amino acid sequences and amino acid compositions of the isolated peptides and by on-line liquid chromatography-mass spectrometry. Incubation of purified peptides with aminopeptidase N resulted in complete hydrolysis of many peptides, while others were only partially hydrolyzed or not hydrolyzed. The tryptic digest of beta-casein exhibits a strong bitter taste, which corresponds to the strong hydrophobicity of several peptides in the tryptic digest of beta-casein. The degradation of the "bitter" tryptic digest by aminopeptidase N resulted in a decrease of hydrophobic peptides and a drastic decrease of bitterness of the reaction mixture.
authors.affiliation: Department of Microbiology, University of Groningen, Haren, The Netherlands.
authors.forename: P S
authors.initials: PS
authors.lastname: Tan
authors.forename: T A
authors.initials: TA
authors.lastname: van Kessel
authors.forename: F L
authors.initials: FL
authors.lastname: van de Veerdonk
authors.forename: P F
authors.initials: PF
authors.lastname: Zuurendonk
authors.forename: A P
authors.initials: AP
authors.lastname: Bruins
authors.forename: W N
authors.initials: WN
authors.lastname: Konings
mesh_terms: D000595:Amino Acid Sequence; D000626:Aminopeptidases / Q000378:metabolism*; D001673:Biodegradation, Environmental; D018826:CD13 Antigens; D002364:Caseins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D005516:Food Microbiology; D006801:Humans; D006868:Hydrolysis; D013294:Lactococcus lactis / Q000201:enzymology* / Q000235:genetics; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000302:isolation & purification / Q000378:metabolism; D013649:Taste; D014357:Trypsin / Q000378:metabolism
chemical_list: D002364:Caseins; D010446:Peptide Fragments; D000626:Aminopeptidases; D018826:CD13 Antigens; D014357:Trypsin