title: Inhibition of bovine trypsin by the phosphorylated N-terminal part beta(1-105) of beta-casein.
abstract: The sensitivities of the R25-I26 bond on bovine beta-casein and on its N-terminal fragment beta(1-105) to trypsin digestion were compared by monitoring the liberation of the beta(1-25) product. It was shown that this peptide bond was poorly and slowly hydrolysed on beta(1-105), while it is highly susceptible to trypsin attack when whole protein is used as substrate. The marked resistance of beta(1-105) is linked to its inhibitory effect on trypsin activity (apparent K'i = 1.2 x 10(-6) M), as demonstrated by using a related chromogenic substrate. Indeed, a preincubation step of trypsin with beta(1-105) leads to a more pronounced inhibitory effect. The progress curves obtained with and without preincubation show that beta(1-105) acts as a slow binding inhibitor on trypsin activity. These findings promise further insight into the action and the regulation of proteolytic enzymes.
authors.affiliation: INRA, Laboratory For Research in Dairy Technology, Rennes, France.
authors.forename: S
authors.initials: S
authors.lastname: Bouhallab
authors.forename: B
authors.initials: B
authors.lastname: Sapin
authors.forename: D
authors.initials: D
authors.lastname: Mollé
authors.forename: G
authors.initials: G
authors.lastname: Henry
authors.forename: J
authors.initials: J
authors.lastname: Léonil
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002364:Caseins / Q000494:pharmacology*; D002417:Cattle; D006868:Hydrolysis; D007700:Kinetics; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000494:pharmacology*; D010766:Phosphorylation; D017386:Sequence Homology, Amino Acid; D014361:Trypsin Inhibitors / Q000494:pharmacology*
chemical_list: D002364:Caseins; D010446:Peptide Fragments; D014361:Trypsin Inhibitors; C106659:beta-casein (1-105)