title: Proteolysis of native proteins. Trapping of a reaction intermediate.
abstract: When limited proteolysis of the mouse major urinary proteins by trypsin was stopped by rapid denaturation of the proteinase, a covalent adduct of the two proteins was observed. The formation of this complex required active trypsin, was favored at low pH, and could be reversed by the addition of covalent or non-covalent trypsin inhibitors. Electrospray mass spectrometry of the complex demonstrated that it was an acyl-enzyme complex, formed after an unusual exopeptidase attack on the C-terminal-Arg-Glu-OH sequence by trypsin. The complex could sequester over 50% of the trypsin in a digestion mixture, and as anticipated, the protein was an effective trypsin inhibitor.
authors.affiliation: Department of Biomolecular Sciences, University of Manchester Institute of Science and Technology, Manchester M60 1QD, United Kingdom.
authors.forename: C
authors.initials: C
authors.lastname: Wu
authors.forename: D H
authors.initials: DH
authors.lastname: Robertson
authors.forename: S J
authors.initials: SJ
authors.lastname: Hubbard
authors.forename: S J
authors.initials: SJ
authors.lastname: Gaskell
authors.forename: R J
authors.initials: RJ
authors.lastname: Beynon
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D006868:Hydrolysis; D013058:Mass Spectrometry; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D011506:Proteins / Q000378:metabolism*; D014357:Trypsin / Q000378:metabolism*
chemical_list: D011506:Proteins; C035737:major urinary proteins; D014357:Trypsin