Potentiometric titration of immobilized cyt <i>c</i>₅₅₂.

<p>SERR spectra of cyt <i>c</i>_<b>552</b> immobilized on 6-mercapto-1-hexanol/1-hexanethiol SAM-coated Ag electrode recorded at electrode potentials of (a) to (d) 250, 300, 350 and 450 mV. All spectra were measured with 413 nm excitation; laser power and accumulation time were 1.5 mW and 30 s, respectively. <b>Inset:</b> relative concentration of ferrous protein (squares) plotted as a function of the electrode potential. The solid line represents a fit of the experimental data to the Nernst equation, yielding <i>E°</i>´ = 262 ± 5 mV, <i>z</i> = 0.70 ± 0.02.