Metal binding ability of metallothionein-3 expressed in Escherichia coli.
Metallothionein-3/growth inhibitory factor is a brain-specific member of the metallothionein gene family, and impairs the survival and neurite formation of cultured neurons. Metallothionein-3 can bind heavy metals such as Zn, Cu, or Cd almost in the same way as other metallothionein family. However, its biological function as growth inhibitory factor apparently distinguishes metallothionein-3 from other metallothioneins. To better understanding of the relationship between the growth inhibitory activity of metallothionein-3 and metals bound to metallothionein-3, the metal-binding ability of metallothionein-3 was analyzed in comparison with those of metallothionein-1 and -2. The metal-binding ability of metallothionein-3 was evaluated by pH titration and 5-5' dithiobis (2-nitrobenzoic) acid (DTNB) analysis as compared with those of the other metallothioneins. The affinity of metal ions for metallothionein-3 was indicated as follows, Cu>Cd>Zn, same as metallothionein-1 and -2. However, the affinity of metallothionein-3 to Cu was much higher than that of metallothionein-1 and -2. The strong affinity to Cu of metallothionein-3 might be related to its growth inhibitory activity.
Toriumi
Shigeru
S
Department of Environmental Medicine and Informatics, Graduate School of Environmental Earth Science, Hokkaido University, Nishi-5, Sapporo 060-0810, Japan.
Saito
Takeshi
T
Hosokawa
Toshiyuki
T
Takahashi
Yasumitsu
Y
Numata
Takuya
T
Kurasaki
Masaaki
M
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D018929:Cell Culture Techniques; D004228:Dithionitrobenzoic Acid / Q000032:analysis; D004795:Enzyme Stability; D004926:Escherichia coli / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008024:Ligands; D008668:Metallothionein / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D019216:Metals, Heavy / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics / Q000378:metabolism; D017354:Point Mutation; D016133:Polymerase Chain Reaction / Q000379:methods; D011817:Rabbits; D017421:Sequence Analysis / Q000379:methods
D008024:Ligands; D019216:Metals, Heavy; D008668:Metallothionein; D004228:Dithionitrobenzoic Acid