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. 

Testiculat androgens are synthesized in the interstitial tissue by the Leydig cells. The immediate precursor of the gonadal steroids, as for the adrenal steroids, is cholesterol. The rate-limiting step, as in the adrenal, is delivery of cholesterol to the inner membrane of the mitochondria by the transport protein StAR. Once in the proper location, cholesterol is acted upon by the side chain cleavage enzyme P450scc. The conversion of cholesterol to pregnenolone is identical in adrenal, ovary, and testis. In the latter two tissues, however, the reaction is promoted by LH rather than ACTH. 

CYPUAl P450scc Cholesterol side-chain cleavage enzyme— Pregnenolone... 

Hammer F, Compagnone NA, Vigne JL, Bair SR, Mellon SH. 2004. Transcriptional regulation of P450scc gene expression in the embryonic rodent nervous system. Endocrinology 145 901-912. 

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. 

It does not bind to intracellular estrogen receptors, but it does bind to sex hormone-binding and corticosteroid-binding globulins. It inhibits P450scc (the cholesterol side chain-cleaving enzyme),... 

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. 

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