CATALYSIS OF PLASTOCYANIN ELECTRON SELF-EXCHANGE BY REDOX-INERT MULTIVALENT CATIONS

Journal article

Electron self-exchange in solutions of the 'blue' copper protein plastocyanin is catalysed by the redox-inert multivalent cations Mg2+ or Co(NH3)3+6. Measurements of specific 1H-NMR line broadening with 50% reduced solutions in the presence of these cations show that electron exchange proceeds through encounters of cation-protein complexes which dissociate at high ionic strength. In the presence of 8mM (5 equivalents/total protein) Co(NH3)3+6, with 10 mM cacodylate (pH*6.0) as background electrolyte, the bimolecular rate constant at 25°C is 7 × 104 M-1·s-1. For comparison, the 'electrostatically screened' rate constant measured in 0.1 M KCl in the absence of added multivalent cations is ~ 4 × 103 M1·s-1. Plastocyanin Electron self-exchange NMR Protein-protein interaction Multivalent cation Blue copper protein. © 1985.

Authors: Armstrong, F; Driscoll, P; Hill, H

• Publication status: Published
• Journal: FEBS LETTERS
• Volume: 190
• Issue: 2
• Pages: 242-248
• Publication date: 1985-01-01
• DOI: 10.1016/0014-5793(85)81292-8
• ISSN: 0014-5793
• Language: English