Reconstitution of apo-superoxide dismutase by nitric oxide-induced copper transfer from metallothioneins.
Chem Res Toxicol
; 13(9): 922-31, 2000 Sep.
Article
en En
| MEDLINE
| ID: mdl-10995266
ABSTRACT
Little is known about copper transfer from Cu-metallothionein (Cu-MT) to various target proteins, such as apo-SOD, and the potential role of redox mechanisms in this transfer. We studied Cu transfer from Cu-MT to apo/Zn-SOD in a cell-free model system and found that Cu(5)-MT and Cu(10)-MT were able to reconstitute SOD activity only in the presence of a nitric oxide donor, (Z)-[N-(3-ammoniopropyl)-N-(n-propyl)amino]diazen-1-ium++ +-1,2-diolate (NOC-15). The percentage of reconstitution by Cu(5)-MT and Cu(10)-MT was 34 and 83%, respectively, compared with that reconstituted by free Cu alone. A Cu chelation assay using bathocuproine disulfonate (BCS) showed that NOC-15 induced release of free Cu from Cu(10)-MT but not from Cu(5)-MT. The transfer of Cu from Cu-MT to apo/Zn-SOD was not accompanied by enhanced Cu-dependent generation of ascorbate radicals or hydroxyl radicals as measured by EPR spectroscopy. We found a 70% decrease in the number of 2,2'-dithiodipyridine titratable SH groups on MT after incubation with NOC-15. Overall, our results suggest that Cu-MT could potentially function in a nitric oxide-dependent pathway for the delivery of Cu to apo-SOD in copper-challenged cells.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Superóxido Dismutasa
/
Cobre
/
Metalotioneína
/
Óxido Nítrico
Límite:
Animals
Idioma:
En
Revista:
Chem Res Toxicol
Asunto de la revista:
TOXICOLOGIA
Año:
2000
Tipo del documento:
Article
País de afiliación:
Estados Unidos