Protection of Mitochondria from Free Hydroxyls by Zn(7)- and Cd(7)- Metallothioneins.
Zn(7)- and Cd(7)-metallothioneins were prepared. Mitochondria were isolated from rat hearts. Mitochondria lipid fluidity, protein conformation and mobility were determined by using ESR spin label. Ca(2+)-Mg(2+)-ATPase activity and (45)Ca uptake activity were assayed. It was found that, after being damaged by hydroxyl radicals, mitochondria lipid fluidity and protein mobility decreased, protein conformation changed and mitochondria Ca(2+)-Mg(2+)-ATPase activity, (45)Ca uptake activity were inhibited. Both Zn(7)- and Cd(7)-metallothioneins could antagonize hydroxyl radicals and protect myocardial mitochondria. However, this effect of Zn(7)-metallothionein was stronger than that of Cd(7)-metallothionein, because the apo-metallothionein has about 10 000 fold higher affinity for Cd than for Zn, so, Zn(7)-metallothionein would release more Zn(2+). More reduced thiol groups would be revealed.
Ge
Shu-Jun
SJ
Department of Biophysics, Beijing Medical University, Beijing 100083, China.
Cheng
Shi
S
Zhong
Chong-Xia
CX
Hou
Lin
L