Cholesterol hydroperoxides as substrates for cholesterol-metabolizing cytochrome P450 enzymes and alternative sources of 25-hydroxycholesterol and other oxysterols

Angew Chem Int Ed Engl. 2015 Sep 14;54(38):11138-42. doi: 10.1002/anie.201505002. Epub 2015 Jul 29.

Abstract

The interaction of the primary autoxidation products of cholesterol, namely 25- and 20ξ-hydroperoxides, with the four principal cholesterol-metabolizing cytochrome P450 enzymes is reported. Addition of cholesterol 25-hydroperoxide to the enzymes CYP27A1 and CYP11A1 induced well-defined spectral changes while generating 25-hydroxycholesterol as the major product. The 20ξ-hydroperoxides induced spectral shifts in CYP27A1 and CYP11A1 but glycol metabolites were detected only with CYP11A1. CYP7A1 and CYP46A1 failed to give metabolites with any of the hydroperoxides. A P450 hydroperoxide-shunt reaction is proposed, where the hydroperoxides serve as both donor for reduced oxygen and substrate. CYP27A1 was shown to mediate the reduction of cholesterol 25-hydroperoxide to 25-hydroxycholesterol, a role of potential significance for cholesterol-rich tissues with high oxidative stress. CYP27A1 may participate in the removal of harmful autoxidation products in these tissues, while providing a complementary source of 25-hydroxycholesterol, a modulator of immune cell function and mediator of viral cell entry.

Keywords: autooxidation; biocatalysis; cholesterol hydroperoxides; cytochrome p450; metabolism.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cholesterol / analogs & derivatives*
  • Cholesterol / metabolism*
  • Cytochrome P-450 Enzyme System / metabolism*
  • Hydroxycholesterols / metabolism*
  • Sterols / metabolism*
  • Substrate Specificity

Substances

  • Hydroxycholesterols
  • Sterols
  • 25-hydroxycholesterol
  • cholesterol hydroperoxide
  • Cytochrome P-450 Enzyme System
  • Cholesterol