Cytochrome P450scc

Cyclic voltammetry and other electrochemical methods offer important and sometimes unique approaches to the electroactive species. Protein organization and kinetic approaches (Correia dos Santos et al. 1999, Schlereth 1999) can also be studied by electrochemical survey. The electron transfer reaction between cytochrome P450scc is an important system for... 

TABLE 6 Surface Density and Area per Molecule of Cytochrome P450scc wild type and Recombinant in LB Film Deposited onto Solid Substrate... 

FiG. 24 CVs of Langmuir-Schaefer films of cytochrome P450scc on indium-tin oxide glass plate (ITO) in 10 mM phosphate buffer containing 0.1 M KCl at a scan rate of 20 mV/s between 0.4 and -0.6 V vs. Ag/AgCl. 

TABLE 7 Redox Peak Potential of Cytochrome P450scc at Different pH of Phosphate Buffer... 

Figure 26 shows the redox potential of 40 monolayers of cytochrome P450scc on ITO glass plate in 0.1 KCl containing 10 mM phosphate buffer. It can be seen that when the cholesterol dissolved in X-triton 100 was added 50 pi at a time, the redox peaks were well distinguishable, and the cathodic peak at -90 mV was developed in addition to the anodic peak at 16 mV. When the potential was scanned from 400 to 400 mV, there could have been reaction of cholesterol. It is possible that the electrochemical process donated electrons to the cytochrome P450scc that reacted with the cholesterol. The kinetics of adsorption and the reduction process could have been the ion-diffusion-controlled process. 

FIG. 26 Cyclic voltammograms of 40 monolayers of Langmuir-Schaefer films of cytochrome P450SCC on indium-tin oxide glass plate (ITO) in 10 mM phosphate buffer at a scan rate of 20 mV/s between 0.4 and —0.4 V vs. Ag/AgCl. LS films on ITO worked as the working electrode, platinum as the counter, and Ag/AgCl as the reference electrode. Cholesterol dissolved in X-triton 100 was added 50 p.1 at a time (1) with cholesterol, (2) 50 p.1 of cholesterol, (3) 100 p.1 cholesterol, and (4) 150 p.1 of cholesterol. 

Lawton BP, Brody EM Assessment of older people. Self-maintaining and instrumental activities of daily living. Gerontology 9 176-186, 1969 Le Goascogne C, Robel P, Gouezou M, et al Neurosteroids cytochrome P450scc in rat brain. Science 237 1212-1214, 1987... 

V. Shumyantseva, G. Deluca, T. Buiko, S. Carrara, C. Nicolini, S.A. Usanov and A. Archakov, Cholesterol amperometric biosensor based on cytochrome P450scc, Biosens. Bioelectron., 19 (2004) 971-976. 

Moore RW, Jefcoate CR, Peterson RE. 1991. 2,3,7,8-Tetrachlorodibenzo-p-dioxin inhibits steroidogenesis in the rat testis by inhibiting the mobilization of cholesterol to cytochrome P450scc. Toxicol Appl Pharmacol 109 85-97. 

Usanov SA, Graham SE, Lepesheva GI, et al. Probing the interaction of bovine cytochrome P450scc (CYP11A1) with adrenodoxin evaluating site-directed mutations by molecular modeling. Biochemistry 2002 41 8310-8320. 

Cytochrome P450scc was purified from mitochondria isolated from bovine adrenal cortex by a published protocol. 

Figure 9.85 Normal phase HPLC profiles of the reaction product of the cholesterol side chain cleavage system. Peaks were identified on the basis of their retention times. (i4) Without cholesterol oxidase treatment. Cholesterol (100 nmol) was incubated with cytochrome P450scc (70 pmol) in the presence of adrenodoxin, adrenodoxin reductase, and an NADPH-generating system. Monitoring was at 214 nm. Peaks 1, cholesterol 2, pregnenolone 3, deoxycorticosterone acetate (internal standard) (B) The reaction mixture of (A) was further incubated with cholesterol oxidase at 37°C for 10 minutes. Monitoring was at 240 nm. Peaks 1, cholestenone 2, progesterone 3, deoxycorticosterone acetate (internal standard). (From Sugano et al., 1989.)...

In mammals, the first and limiting step in the bios)mthesis of all C21 and C20 steroids is the conversion of cholesterol into pregnenolone. Cholesterol is also supposed to be a precursor of pregnanes, cardenolides and steroid saponins in plants. Analogous to the formation of steroids in animals, this reaction is thought to be catalysed by side-chain cleavage cytochrome P450scc (SCCE). 

Schwarz D, Kisselev P, Wessel R, Pisch S, Bornscheur U, Schmid RD. Possible involvement of nonbilayer lipids in the stimulation of the activity of cytochrome P450SCC (CYPl 1A1) and its propensity to induce vesicle aggregation. Chem Phys Lipids 1997 85 91-99. 

Brentano, S. T., and Miller, W. L. (1992). Regulation of human cytochrome P450scc and adrenodoxin messenger ribonucleic acids in JEG-3 cytotrophoblast cells. Endocrinology 131, 3010-3018. 

Cytochrome P450 22A1 (the trivial name of which is cytochrome P450scc) was identified in human and bovine adrenal mitochondria. This enzyme mediates the cleavage of the cholesterol side chain to pregnenolone, which is the first stage in the biosynthesis of several steroidal hormones. 

Carrara, S., Shumyantseva, V.V., Archakov, A.I., and Samori, B. (2008) Screen-printed electrodes based on carbon nanotubes and cytochrome P450SCC for highly sensitive cholesterol biosensors. Biosens. Bioelectron., 24, 148-150. 

Coghlan VM, Vickery LE (1991) Site-specific mutations in human ferredoxin that affect binding to fer-redoxin reductase and cytochrome P450scc. J Biol Chem 266 18606-18612... 

Headlam MJ, Wilce MCJ, Tuckey RC (2003) The E-G loop region of cytochrome P450scc (CY-PllAl) interacts with the phospholipid membrane. Biochim Biophys Acta 1617 96-108... 

Maines MD, Sluss PM, Iscan M (1990) cw-Plat-inum-mediated decrease in serum testosterone is associated with depression of luteinizing hormone receptors and cytochrome P450scc in rat testis. Endocrinology 126 2398-2406... 

Guryev O, Carvalho RA, Usanov S, GilepA, Estabrook RW (2003) A pathway for the metabolism of vitamin Dj unique hydroxylated metabolites formed during catalysis with cytochrome P450scc (CYPllAl). Proc Natl Acad Sci U S A 100 14754-14759... 

Slominski AT, Kim TK, Chen J, Nguyen MN, Li W, Yates CR, Sweatman T, Janjetovic Z., Tuckey RC (2012) Cytochrome P450scc-dependent metabolism of 7-dehydrocholesterol in placenta and epidermal keratinocytes. Int J Biochem Cell Biol 44 2003-2018... 

Shumyantseva V et al (2004) Cholesterol amperomet-ric biosensor based on cytochrome P450scc. Biosens Bioelectron 19(9) 971-976... 

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