Layer-by-Layer Arrangement by Protein−Protein Interaction of Sulfite Oxidase and Cytochrome c Catalyzing Oxidation of Sulfite

Fabrication of cytochrome c-poly(5-amino-2-napthalenesulfonic acid) electrode by one step procedure and direct electrochemistry of cytochrome c

“…From the mass change of PANS and cyt c-PANS electrode, we measured amount of entrapment of cyt c and found to be ≈100 ng. The entrapped amount of cyt c was comparable with previously reported literature by two step protocol that cyt c/poly(terthiophene-3-carboxylic acid) {poly (TTCA)} micro electrode (Koh et al, 2008), protein modified electrode (Dronov et al, 2008), SAM/DNA/cyt c electrode (126 ng) (Ding et al, 2006) and with cyt c/C 60 -Pd modified electrode ( m, 135 ng) (Souzaa et al, 2005). The mass changes from the frequency were calculated by using the Sauerbrey equation (Sauerbrey, 1959;Okahata and Ebato, 1989).…”

“…There are number of modified interfaces available to immobilize cyt c such as -CO 2 H terminated self assembled monolayers (SAMs) through electrostatic interactions between carboxylate and the exterior of the protein (Collinson et al, 1992;Yamamoto et al, 2001;El Kasmi et al, 1998), layer by layer surface (Lvov et al, 1998), or multilayer film surface (Beissenhirtz et al, 2004), on the surface of DNA modified electrode (Lisdat et al, 2001(Lisdat et al, , 1999aChen and Chen, 2003;Liu et al, 2003), by covalent linkage (McNeil et al, 1995;Koh et al, 2008), protein modification (Heller, 1990Dronov et al, 2008), and on the surface of inorganic porous material (Xu et al, 2003;Yu and Ju, 2002). Although these new materials have been proven to be excellent as the immobilization matrices due to their high stability and good absorbability, some inherent defects are inevitable for the application of these multilayer and inorganic porous materials in electrochemical sensing such as low conductivity in inorganic material and in thicker films or multilayers, generally only protein molecules near the electrode surface are electroactive.…”

The Mononuclear Molybdenum Enzymes

“…More recently, sulfite oxidase and cytochrome c have been coimmobilized in molecular layers onto a specially treated electrode. 293 Addition of sulfite results in a catalytic wave that can be observed even at very rapid scan rates, indicating that the enzyme, once reduced by sulfite, efficiently passes electrons on to cytochrome c then on to the electrode. The catalytic current is dependent on sulfite concentration below 2 mM, with an effective K m of approximately 310 μM.…”

Molybdenum enzymes in higher organisms

“…Given that the amplitude of the catalytic wave indicated only ~5% of the immobilized enzyme was engaged in turnover, it was concluded that the enzyme was immobilized with its heme domain proximal to the electrode surface with no direct electrochemical contact between the molybdenum center and the electrode, with only a small portion of the enzyme population was considered to be in a configuration where the two redox-active centers of the enzyme were close enough for intramolecular electron transfer to occur. More recently, sulfite oxidase and cytochrome c have been coimmobilized in molecular layers onto a specially treated electrode possessing a monolayer of cytochrome c [196]. While a layer of enzyme appears to promote deposition of a second layer of cytochrome c , this and subsequent layers of the cytochrome appear to be insulated from the electrode-proximal monolayer.…”