Ascorbate-induced high-affinity binding of copper to cytosolic proteins
| Autor: | Hideo Iwahashi, Noriyuki Shiraishi, In Sook Matsui Lee, Yoko Inai, Yuriko Ohta, Morimitsu Nishikimi |
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| Rok vydání: | 2001 |
| Předmět: |
Biophysics
chemistry.chemical_element Ascorbic Acid Biochemistry Redox Antioxidants chemistry.chemical_compound Mice Cytosol Animals Humans Chelation Molecular Biology Chelating Agents Fluorescent Dyes chemistry.chemical_classification Brain Chemistry Brain Proteins Cell Biology Glutathione Blood Proteins Ascorbic acid Fluoresceins Copper Spectrometry Fluorescence chemistry Liver Thiol Oxidation-Reduction Intracellular Protein Binding |
| Zdroj: | Biochemical and biophysical research communications. 287(4) |
| ISSN: | 0006-291X |
| Popis: | Copper chaperones are necessary for intracellular trafficking of copper to target proteins. This is probably because the milieu inside the cell has a large capacity for sequestering this metal. By fluorometry using a fluorescent Cu(II) chelator and by centrifugal ultrafiltration, we have studied copper binding of the whole cytosolic proteins from mouse brain and liver, and found that their binding capacity and affinity for copper were markedly increased by ascorbate. Brain cytosolic protein bound, with high affinity, 63 nmol of copper/mg, more than half of which was redox-inactive, as indicated by its inability to catalyze oxidation of ascorbate. Most of the bound copper was in the Cu(I) state, coordinating to thiol groups of protein. Cytosolic protein competed for copper more strongly than GSH when compared at their relative concentrations in tissues. The results taken together suggest that protein thiols of cytosol can strongly sequester copper. |
| Databáze: | OpenAIRE |
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