Stimulation of peroxidation in rat liver microsomes by (copper, zinc)-metallothioneins.
The abilities of pig liver (copper, zinc) metallothionein I and rat liver zinc metallothionein II to modify lipid peroxidation in incubations of liver microsomes have been compared with the activities of reduced glutathione, mannitol, quinacrine, EDTA, dimethyl-pyrroline-N-oxide and phenyl-butyl-nitrone. Lipid peroxidation was determined by assay of thiobarbituric acid reactive substance formation in incubations of microsomes with iron/ADP or a mixture of xanthine and xanthine oxidase. Zinc metallothionein II had no effect on the extent of peroxidation in either system but (copper, zinc) metallothionein I caused a stimulation of peroxidation initiated by xanthine and xanthine oxidase, all other compounds tested were inhibitory. Gel exclusion chromatography of incubations of (copper, zinc) metallothionein I with xanthine and xanthine oxidase revealed aggregation of the metalloprotein. This may have exposed copper in a form capable of initiating peroxidation.
D000818:Animals; D007700:Kinetics; D015227:Lipid Peroxidation / Q000187:drug effects; D008668:Metallothionein / Q000494:pharmacology / Q000502:physiology*; D008862:Microsomes, Liver / Q000378:metabolism*; D051381:Rats; D012016:Reference Values; D013552:Swine
D008668:Metallothionein