1H-NMR assignments and secondary structure of human plasminogen kringle 1.
The 1H-NMR spectrum of the kringle 1 domain of human plasminogen complexed with 6-aminohexanoic acid, an antifibrinolytic drug, has been assigned. Elements of secondary structure have been identified on the basis of sequential, medium and long-range dipolar interactions, back-bone amide spin-spin couplings (3JHN-H alpha) and 1H-2H exchange rates. The kringle contains scarcely any repetitive secondary structure: eight reverse turns and two short beta-sheets. These comprise 40% and 12% of the domain, respectively. No alpha-helix was found. An aromatic cluster formed by His31, Phe36, Trp62, Phe64, Tyr72 and Tyr74 is indicated by several inter-residue Overhauser connectivities. Contacts between the methyl groups of Leu46 and the side chains of Phe36, Trp62 and Trp25 are observed. A second hydrophobic cluster formed by Tyr9, Ile77 and Leu78 is also indicated. A comparison of secondary structure elements among plasminogen kringles 1 and 4 and tissue-type plasminogen activator kringle 2 suggests that there is variability in the position and number of reverse turns on going from one kringle to another; however, the beta-sheets are conserved among the homologs.
Rejante
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Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213-3890.
Llinás
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D000595:Amino Acid Sequence; D006801:Humans; D018082:Kringles; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D010958:Plasminogen / Q000737:chemistry*; D017433:Protein Structure, Secondary; D017386:Sequence Homology, Amino Acid
D010958:Plasminogen