Branched phosphatidylcholines stimulate activity of cytochrome P450SCC (CYP11A1) in phospholipid vesicles by enhancing cholesterol binding, membrane incorporation, and protein exchange.

The Journal of Biological Chemistry
Pyotr KisselevDieter Schwarz

Abstract

Phosphatidylcholines (PCs) with branched fatty acyl chains substituted in the two positions of the main chains (branched PCs) have been shown to be potent activators of the side chain cleavage activity of cytochrome P450SCC (CYP11A1) (Schwarz, D., Kisselev, P., Wessel, R., Jueptner, O., and Schmid, R. D. (1996) J. Biol. Chem. 271, 12840-12846). The present study reports on the effect of a series of branched PC on cholesterol binding, membrane integration, and protein exchange in large unilamellar vesicles prepared by an extrusion technique. Enzyme kinetics using vesicles as well as optical titration using a micelle system with the detergent Tween 20 demonstrate that activation is correlated with the fraction of P450SCC in the high spin form. The potency of branched PCs both to activate the enzyme and to induce spin state changes increases with increasing lengths of both the branched and main fatty acyl chains. We found that the extent as well as the rate of integration of P450SCC into vesicle membranes studied by gel chromatography and stopped flow kinetics were increased by branched PC. Finally, it is demonstrated by measurement of the enzymatic activity in primary and secondary vesicles that branched PCs are potent in retaini...Continue Reading

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Citations

May 12, 2000·European Journal of Biochemistry·R M EpandD Schwarz
Dec 8, 2009·Journal of Molecular Biology·Andrew J AnnaloraC David Stout
Jun 5, 2014·The FEBS Journal·Elaine W TieuRobert C Tuckey
Nov 26, 2003·Biochimica Et Biophysica Acta·Madeleine J HeadlamRobert C Tuckey
Nov 7, 2016·Molecular and Cellular Endocrinology·Yu ChienBon-Chu Chung
Oct 10, 2002·The Journal of Biological Chemistry·Robert C TuckeyWalter L Miller
Sep 15, 2001·Archives of Biochemistry and Biophysics·A E AitkenB S Masters

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