Label-free surface-enhanced infrared spectro-electro-chemical analysis of the Redox potential shift of cytochrome <em> c</em> complexed with a cardiolipin-containing lipid membrane of varied composition

Label-free surface-enhanced infrared spectro-electro-chemical analysis of the Redox potential shift of cytochrome c complexed with a cardiolipin-containing lipid membrane of varied composition

Liu Li, Wu Lie, Zeng Li, Jiang Xiu-E†

The potential-induced surface-enhanced infrared adsorption (SEIRA) difference spectra of cyt c -containing (black curve) and blank films (grey curve) CL_PC-DT(10) (curve a ), CL_PC-DT(20) (curve b ), CL_PC-DT(40) (curve c ), and Cyt c -MUA (curve d ) in 10-mM PB (pH 7), with the reference potential −0.1 V and the sample potential 0.35 V (curve a ), 0.4 V (curve b ), 0.5 V (curve c ), and 0.1 V (curve d ). The arrow corresponds to absorbance Δ A of 5 × 10⁻⁴. Inset: the ratio Δ I _O−H/ I ₁₆₉₃ versus 1-dodecanethiol (DT) concentration, where Δ I _O−H is the difference in the intensity of negative peaks at ∼3500 cm⁻¹ between the complexes Cyt c -CL_PC-DT and CL_PC-DT, and I ₁₆₉₃ is the intensity at 1693 cm⁻¹. CL_PC: cardiolipin-phosphatidylcholine bilayer, MUA: 11-mercaptoundecanoic acid.