title: Purification and characterization of cadmium-binding protein from unicelluar alga Chlorella sorokinian.
abstract: The unicellular green alga Chlorella sorokiniana ANA9 is highly resistant to heavy metals, and its metal-binding proteins are induced in the presence of cadmium. A novel cadmium-binding protein in C. sorokiniana cultured in 100 mg/l cadmium ions for 4 days was isolated and characterized. The crude protein extract was obtained by cell disruption and partly purified by ammonium sulfate precipitation. After purification by anion-exchange chromatography with diethylaminoethyl (DEAE)-Sepharose CL-6B, the protein was further purified by gel filtration with Sephacryl S-100, followed by Sephadex G-75. The molecular weight of the purified protein was determined to be 11.5 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The cadmium binding capacity of the purified protein was 119 microg/mg. The involvement of thiol coordination in metal-ion binding was confirmed by measuring the ultraviolet spectrum. This article is the first to describe the metallothionein-like cadmium-binding protein from Chlorella species, the expression of which is induced by cadmium exposure.
authors.affiliation: Department of Biochemistry and Applied Biosciences, University of Miyazaki, 1-1 Gakuen Kibanadai-Nishi, Miyazaki, 889-2192, Japan. a04109u@cc.miyazaki-u.ac.jp
authors.forename: Naoto
authors.initials: N
authors.lastname: Yoshida
authors.forename: Kazushige
authors.initials: K
authors.lastname: Ishii
authors.forename: Tomoko
authors.initials: T
authors.lastname: Okuno
authors.forename: Kazunori
authors.initials: K
authors.lastname: Tanaka
mesh_terms: D002708:Chlorella / Q000737:chemistry*; D008668:Metallothionein / Q000737:chemistry / Q000302:isolation & purification*; D008970:Molecular Weight; D020539:Sequence Analysis, Protein
chemical_list: C004203:cadmium-binding protein; D008668:Metallothionein