title: Significance of alpha-fragment of metallothionein in cadmium binding.
abstract: In order to evaluate the significance of alpha- and beta-fragments of metallothionein with regard to Cd binding in biosynthetic processes, the Cd-binding ability of four mutant metallothioneins was examined using the Escherichia coli expression system. The features of the mutant metallothioneins were proteins in which cysteine residues in the alpha- or beta-fragment were replaced with alanine residues, or that the sequential order of the fragments was altered. The expressed mutant metallothioneins having an intact alpha-fragment showed the constructive abilities of the Cd-thiolate cluster. On the other hand, mutant metallothionein having an alpha-fragment lacking metal-binding sites exhibited no Cd-binding ability. The condition for maintaining the Cd-binding capability of metallothionein was that the alpha-fragment remains intact irrespective of the sequential order of the two fragments. The alpha-fragment is an indispensable component in metal-binding processes of Cd-metallothionein.
authors.affiliation: Department of Environmental Medicine and Informatics, Graduate School of Environmental Earth Science, Hokkaido University, Sapporo, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Kurasaki
authors.forename: R
authors.initials: R
authors.lastname: Yamaguchi
authors.forename: A R
authors.initials: AR
authors.lastname: Linde Arias
authors.forename: M
authors.initials: M
authors.lastname: Okabe
authors.forename: Y
authors.initials: Y
authors.lastname: Kojima
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D002104:Cadmium / Q000378:metabolism*; D004926:Escherichia coli; D008668:Metallothionein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism*; D013056:Spectrophotometry, Ultraviolet; D013329:Structure-Activity Relationship
chemical_list: D010446:Peptide Fragments; D002104:Cadmium; D008668:Metallothionein