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Metal Binding Ability of Metallothionein‐3 Expressed in Escherichia coli
Author(s) -
Toriumi Shigeru,
Saito Takeshi,
Hosokawa Toshiyuki,
Takahashi Yasumitsu,
Numata Takuya,
Kurasaki Masaaki
Publication year - 2005
Publication title -
basic and clinical pharmacology and toxicology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.805
H-Index - 90
eISSN - 1742-7843
pISSN - 1742-7835
DOI - 10.1111/j.1742-7843.2005.pto960404.x
Subject(s) - metallothionein , metal , chemistry , metalloprotein , biochemistry , gene , enzyme , organic chemistry
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.