ISSN:
1432-1327
Keywords:
Key words CuA domain
;
Thermus thermophilus
;
Cytochrome ba3
;
Electrochemistry
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Abstract The electrochemistry of a water-soluble fragment from the CuA domain of Thermus thermophilus cytochrome ba 3 has been investigated. At 25 °C, CuA exhibits a reversible reduction at a pyridine-4-aldehydesemicarbazone-modified gold electrode (0.1 M Tris, pH 8) with E° = 0.24 V vs NHE. Thermodynamic parameters for the [Cu(Cys)2Cu]+/0 electrode reaction were determined by variable-temperature electrochemistry (ΔS°rc = –5.4(12) eu, ΔS° = –21.0(12) eu, ΔH° = –11.9(4) kcal/mol;ΔG° = –5.6 (11) kcal/mol). The relatively small reaction entropy is consistent with a low reorganization energy for [Cu(Cys)2Cu]+/0 electron transfer. An irreversible oxidation of [Cu(Cys)2Cu]+ at 1 V vs NHE confirms that the CuII:CuII state of CuA is significantly destabilized relative to the CuII state of analogous blue-copper proteins.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s007750050088
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