title: Structure of cobra cardiotoxin CTX I as derived from nuclear magnetic resonance spectroscopy and distance geometry calculations.
abstract: The structure of cardiotoxin CTX I from Naja naja atra has been investigated by NMR spectroscopy. Sequence specific resonance assignments have been obtained for all backbone protons as well as for most side-chain protons. Distance geometry calculations were carried out using a metric matrix DG program. A total of 715 NOE constraints, 27 phi angle constraints and a list of the hydrogen bond donors were used for the metric matrix DG calculations and refinement. The average pairwise r.m.s.d. of the resulting structures was 1.01 A for the backbone heavy atoms, and 1.69 A for all heavy atoms. The protein is rich in beta structure and consists of a large triple-stranded, antiparallel beta sheet as well as a short double-stranded, antiparallel beta sheet. Non-regular hydrogen bonding is found between side-chains of the carboxy-terminal end and the rest of the core region. The structure is discussed in terms of evolutionary aspects as well as recent investigations about the biological function and active site.
authors.affiliation: Institut für Organische Chemie und Biochemie, TU München, Garching, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Jahnke
authors.forename: D F
authors.initials: DF
authors.lastname: Mierke
authors.forename: L
authors.initials: L
authors.lastname: Béress
authors.forename: H
authors.initials: H
authors.lastname: Kessler
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D005075:Biological Evolution; D004179:Cobra Cardiotoxin Proteins / Q000737:chemistry*; D017815:Elapidae; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D015394:Molecular Structure; D017433:Protein Structure, Secondary
chemical_list: D004179:Cobra Cardiotoxin Proteins