title: Kringle-2 domain of the tissue-type plasminogen activator. 1H-NMR assignments and secondary structure.
abstract: A recombinant 90-residue polypeptide fragment containing the three-loop kringle-2 domain of human tissue-type plasminogen activator (t-PA) has been studied by two-dimensional 1H-NMR spectroscopy at 500 MHz. Complete sequence-specific resonance assignments were derived. Overall, the kringle exhibits a compact, folded conformation with more than 50% of the residues in irregular structures. Elements of secondary structure were identified from sequential, medium- and long-range dipolar (Overhauser) interproton interactions. These identifications were corroborated by analysis of spin-spin scalar 3J alpha N splittings and identification of backbone amide NH protons exhibiting retarded 1H/2H exchange in 2H2O. Three antiparallel beta-sheets and six tight turns were located. In addition, one short alpha-helical region was found in the Ser43-Ala44-Gln44a-Ala44b-Leu44c-Gly45+ ++ segment; this region contains three-residue insertions unique to the t-PA and urokinase kringles. Although the secondary structure of the t-PA kringle 2 in solution is in overall agreement with that observed in the crystallographic structure of the prothrombin kringle 1 [Tulinsky, A., Park, C.H. & Skrzypczak-Jankun, E. (1988) J. Mol. Biol. 202, 885-901], the alpha-helical segment and other details of the secondary structure differ somewhat from the prothrombin homolog.
authors.affiliation: Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213-3890.
authors.forename: I J
authors.initials: IJ
authors.lastname: Byeon
authors.forename: R F
authors.initials: RF
authors.lastname: Kelley
authors.forename: M
authors.initials: M
authors.lastname: Llinás
mesh_terms: D000595:Amino Acid Sequence; D004220:Disulfides / Q000032:analysis; D006859:Hydrogen; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011789:Quantum Theory; D011994:Recombinant Proteins / Q000737:chemistry; D010959:Tissue Plasminogen Activator / Q000737:chemistry*
chemical_list: D004220:Disulfides; D011994:Recombinant Proteins; D006859:Hydrogen; D010959:Tissue Plasminogen Activator