Temperature-Driven Changeover in the Electron-Transfer Mechanism of a Thermophilic Plastocyanin.
Electron-transfer kinetics of the thermophilic protein Plastocyanin from Phormidium laminosum adsorbed on 1,ω-alkanedithiol self-assembled monolayers (SAMs) deposited on gold have been investigated. The standard electron-transfer rate constant has been determined as a function of electrode-protein distance and solution viscosity over a broad temperature range (0-90 °C). For either thin or thick SAMs, the electron-transfer regime remains invariant with temperature, whereas for the 1,11-undecanethiol SAM of intermediate chain length, a kinetic regime changeover from a gated or friction-controlled mechanism at low temperature (0-30 °C) to a nonadiabatic mechanism above 40 °C is observed. To the best of our knowledge, this is the first time a thermal-induced transition between these two kinetic regimes is reported for a metalloprotein.
†Departamento de Quı́mica Fı́sica, Universidad de Sevilla, c/Profesor Garcı́a González, 1, 41012 Sevilla, Spain.
José Luis
JL
Olloqui-Sariego
‡Instituto de Bioquı́mica Vegetal y Fotosı́ntesis, cicCartuja, Universidad de Sevilla y C.S.I.C, Avd. Américo Vespucio 49, 41092 Sevilla, Spain.
Blas
B
Moreno-Beltrán
‡Instituto de Bioquı́mica Vegetal y Fotosı́ntesis, cicCartuja, Universidad de Sevilla y C.S.I.C, Avd. Américo Vespucio 49, 41092 Sevilla, Spain.
Antonio
A
Díaz-Quintana
‡Instituto de Bioquı́mica Vegetal y Fotosı́ntesis, cicCartuja, Universidad de Sevilla y C.S.I.C, Avd. Américo Vespucio 49, 41092 Sevilla, Spain.
Miguel A
MA
De la Rosa
†Departamento de Quı́mica Fı́sica, Universidad de Sevilla, c/Profesor Garcı́a González, 1, 41012 Sevilla, Spain.
Juan José
JJ
Calvente
†Departamento de Quı́mica Fı́sica, Universidad de Sevilla, c/Profesor Garcı́a González, 1, 41012 Sevilla, Spain.
Rafael
R
Andreu
1,ω-alkanedithiol monolayer; kinetic regime changeover; protein electron transfer; solution viscosity; temperature; thermophilic plastocyanin