title: The NMR structure of the activation domain isolated from porcine procarboxypeptidase B.
abstract: The three-dimensional structure of the activation domain isolated from porcine pancreatic procarboxypeptidase B was determined using 1H NMR spectroscopy. A group of 20 conformers is used to describe the solution structure of this 81 residue polypeptide chain, which has a well-defined backbone fold from residues 11-76 with an average root mean square distance for the backbone atoms of 1.0 +/- 0.1 A relative to the mean of the 20 conformers. The molecular architecture contains a four-stranded beta-sheet with the polypeptide segments 11-17, 36-39, 50-56 and 75-76, two well defined alpha-helices from residues 20-30 and 60-70, and a 3(10) helix from residues 43-46. The three helices are oriented almost exactly antiparallel to each other, are all on the same side of the beta-sheet, and the helix axes from an angle of approximately 45 degrees relative to the direction of the beta-strands. Three segments linking beta-strands and helical secondary structures, with residues 32-35, 39-43 and 56-61, are significantly less well ordered than the rest of the molecule. In the three-dimensional structure two of these loops (residues 32-35 and 56-61) are located close to each other near the protein surface, forming a continuous region of increased mobility, and the third disordered loop is separated from this region only by the peripheral beta-strand 36-39 and precedes the short 3(10) helix.
authors.affiliation: Institut für Molekularbiologie und Biophysik, Eidgenössische, Technische Hochschule--Hönggerberg, Zürich, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Vendrell
authors.forename: M
authors.initials: M
authors.lastname: Billeter
authors.forename: G
authors.initials: G
authors.lastname: Wider
authors.forename: F X
authors.initials: FX
authors.lastname: Avilés
authors.forename: K
authors.initials: K
authors.lastname: Wüthrich
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D043424:Carboxypeptidase B; D002268:Carboxypeptidases / Q000737:chemistry* / Q000378:metabolism; D004789:Enzyme Activation; D004792:Enzyme Precursors / Q000737:chemistry* / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010179:Pancreas / Q000201:enzymology; D011487:Protein Conformation; D013552:Swine
chemical_list: D004792:Enzyme Precursors; D002268:Carboxypeptidases; D043424:Carboxypeptidase B