Abstract
Rate constants and activation parameters are compared for the reductions of native and type 2 copper-depleted (T2D) Rhus vernicifera laccase type 1 Cu(II) by hydroxyethylferrocene, Fe(CN)64- and Fe(EDTA)2-. Oxidation of Fe(CN)64- (k(25°C)=1.45 · 102 M-1 · s-1, pH 7, I = 0.5 M) by T2D laccase blue copper is an order of magnitude faster than the corresponding native enzyme rate, and a type 2 Cu(II)-Fe(CN)64- interaction is shown to be responsible for complex kinetic behavior in the reduction of native laccase. Activation parameters (ΔH‡, ΔS‡) confirm the presence of a large conformational rearrangement barrier in the electron transfer pathway to laccase type 1 Cu(II), as compared with other blue copper proteins. A systematic compensation pattern between ΔH‡ and ΔS‡ in laccase reductions by Fe(II) redox agents suggests a common mechanism, with considerable flexibility in activation requirements, dependent upon the hydrophilicity of the electron donor.
Original language | English (US) |
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Pages (from-to) | 112-116 |
Number of pages | 5 |
Journal | Biochimica et Biophysica Acta (BBA)/Protein Structure and Molecular |
Volume | 791 |
Issue number | 1 |
DOIs | |
State | Published - Nov 23 1984 |
Keywords
- (R vernicifera)
- Electron transfer rate
- Hydroxyethyl ferrocene
- Laccase reduction
ASJC Scopus subject areas
- Biophysics
- Structural Biology
- Biochemistry
- Molecular Biology