title: Comparison of the solution conformations of human [Zn7]-metallothionein-2 and [Cd7]-metallothionein-2 using nuclear magnetic resonance spectroscopy.
abstract: The solution structure of native human [Zn7]-metallothionein-2 has been compared with the previously determined structure of human [Cd7]-metallothionein-2. The comparison was based on complete sequence-specific 1H nuclear magnetic resonance assignments for human [Zn7]-metallothionein-2 obtained using the sequential assignment method. The secondary structure was found to be very similar in the [Zn7]- and [Cd7]- forms of the protein. Only seven amide protons in [Zn7]- metallothionein-2 were found to have exchange rates lower than approximately 0.2 min-1 at pH 7.0 and 10 degrees C, which corresponds closely to the results of amide proton exchange studies with the [Cd7]- form of the protein. Finally, the 1H-1H distance constraints determined from nuclear Overhauser enhancement spectroscopy for human [Zn7]-metallothionein-2 were checked for compatibility with the [Cd7]-metallothionein-2 structure. Overall, although no direct method is available for identifying the metal-polypeptide co-ordinative bonds in the Zn(2+)-containing protein, these measurements provided several independent lines of evidence showing that the [Zn7]- and [Cd7]- forms of human metallothionein-2 have the same molecular architecture.
authors.affiliation: Institut für Molekularbiologie und Biophysik, Eidgenössische Technische Hochschule-Hönggerberg, Zürich, Switzerland.
authors.forename: B A
authors.initials: BA
authors.lastname: Messerle
authors.forename: A
authors.initials: A
authors.lastname: Schäffer
authors.forename: M
authors.initials: M
authors.lastname: Vasák
authors.forename: J H
authors.initials: JH
authors.lastname: Kägi
authors.forename: K
authors.initials: K
authors.lastname: Wüthrich
mesh_terms: D000577:Amides / Q000737:chemistry; D000595:Amino Acid Sequence; D002104:Cadmium / Q000737:chemistry*; D006801:Humans; D046911:Macromolecular Substances; D009682:Magnetic Resonance Spectroscopy; D008668:Metallothionein / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D015032:Zinc / Q000737:chemistry*
chemical_list: D000577:Amides; D046911:Macromolecular Substances; C004203:cadmium-binding protein; C021267:zinc thionein; D002104:Cadmium; D008668:Metallothionein; D015032:Zinc