title: Evidence for the extent of insertion of the active site loop of intact alpha 1 proteinase inhibitor in beta-sheet A.
abstract: The extent of insertion of beta-strand s4A into sheet A in intact serpin alpha 1-proteinase inhibitor (alpha 1PI has been probed by peptide annealing experiments [Schulze et al. (1990) Eur. J. Biochem. 194, 51-56]. Twelve synthetic peptides of systematically varied length corresponding in sequence to the unprimed (N-terminal) side of the active site loop were complexed with alpha 1PI. The complexes were then characterized by circular dichroism spectroscopy and tested for inhibitory activity. Four peptides formed complexes which retained inhibitory activity, one of which was nearly as effective as the native protein. Comparison with the three dimensional structures of cleaved alpha 1PI [Löbermann et al. (1984) J. Mol. Biol. 177, 531-556] and plakalbumin [Wright et al. (1990) J. Mol. Biol. 213, 513-528] supports a model in which alpha 1PI requires the insertion of a single residue, Thr345, into sheet A for activity.
authors.affiliation: Max-Planck-Institut für Biochemie, Martinsried bei München, Germany.
authors.forename: A J
authors.initials: AJ
authors.lastname: Schulze
authors.forename: P W
authors.initials: PW
authors.lastname: Frohnert
authors.forename: R A
authors.initials: RA
authors.lastname: Engh
authors.forename: R
authors.initials: R
authors.lastname: Huber
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002942:Circular Dichroism; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010179:Pancreas / Q000201:enzymology; D010196:Pancreatic Elastase / Q000378:metabolism; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry*; D011487:Protein Conformation; D013056:Spectrophotometry, Ultraviolet; D013552:Swine; D013917:Thrombin / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism; D000515:alpha 1-Antitrypsin / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology
chemical_list: D010455:Peptides; D000515:alpha 1-Antitrypsin; D010196:Pancreatic Elastase; D014357:Trypsin; D013917:Thrombin