title: 1H, 13C and 15N resonance assignments and secondary structure analysis of CmPI-II, a serine protease inhibitor isolated from marine snail Cenchritis muricatus.
abstract: A protease inhibitor (CmPI-II) (UNIPROT: IPK2_CENMR) from the marine mollusc Cenchritis muricatus, has been isolated and characterized. It is the first member of a new group (group 3) of non-classical Kazal-type inhibitors. CmPI-II is a tight-binding inhibitor of serine proteases: trypsin, human neutrophil elastase (HNE), subtilisin A and pancreatic elastase. This specificity is exceptional in the members of Kazal-type inhibitor family. Several models of three-dimensional structure of CmPI-II have been constructed by homology with other inhibitors of the family but its structure has not yet been solved experimentally. Here we report the (1)H, (15)N and (13)C chemical shift assignments of CmPI-II as basis for NMR structure determination and interaction studies. Secondary structure analyses deduced from the NMR chemical shift data have identified three β-strands β1: residues 14-19, β2: 23-35 and β3: 43-45 and one helix α1: 28-37 arranged in the sequential order β1-β2-α1-β3. These secondary structure elements suggest that CmPI-II adopts the typical scaffold of a Kazal-type inhibitor.
authors.affiliation: Centro de Estudios de Proteínas, Facultad de Biología, Universidad de La Habana, Ciudad de La Habana-Cuba, 25 No. 455, Vedado, Havana, Cuba.
authors.forename: Aymara
authors.initials: A
authors.lastname: Cabrera-Muñoz
authors.affiliation: Centro de Estudios de Proteínas, Facultad de Biología, Universidad de La Habana, Ciudad de La Habana-Cuba, 25 No. 455, Vedado, Havana, Cuba.
authors.forename: Laritza
authors.initials: L
authors.lastname: Rojas
authors.affiliation: Centro de Estudios de Proteínas, Facultad de Biología, Universidad de La Habana, Ciudad de La Habana-Cuba, 25 No. 455, Vedado, Havana, Cuba.
authors.forename: Maday
authors.initials: M
authors.lastname: Alonso-del-Rivero Antigua
authors.affiliation: Instituto de bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho, 373 - Bloco E, sala 10, 21941-902, Rio de Janeiro, RJ, Brazil. jrmpires@cnrmn.bioqmed.ufrj.br.
authors.forename: José Ricardo
authors.initials: JR
authors.lastname: Pires
mesh_terms: D000818:Animals; D019906:Nuclear Magnetic Resonance, Biomolecular; D017433:Protein Structure, Secondary; D015842:Serine Proteinase Inhibitors / Q000737:chemistry*; D012908:Snails
chemical_list: D015842:Serine Proteinase Inhibitors
keywords: Kazal-type protease inhibitor; NMR assignments; Protein structure; Serine protease inhibitor