Journal article Open Access

Electron Leakage from the Mitochondrial NADPH-Adrenodoxin Reductase-Adrenodoxin-P450scc (Cholesterol Side Chain Cleavage) System

Hanukoglu, I.; Rapoport, R.; Weiner, L.; Sklan, D.


Dublin Core Export

<?xml version='1.0' encoding='utf-8'?>
<oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
  <dc:creator>Hanukoglu, I.</dc:creator>
  <dc:creator>Rapoport, R.</dc:creator>
  <dc:creator>Weiner, L.</dc:creator>
  <dc:creator>Sklan, D.</dc:creator>
  <dc:date>1993-09-01</dc:date>
  <dc:description>In electron (e-) transfer systems some e- may "leak" reducing O2 to superoxide radical. This study examined the sites and kinetics of e- leakage from the mitochondrial P450scc system. Adrenodoxin reductase alone oxidized NADPH reducing O2 to superoxide radical at a very low rate. However, the reductase-adrenodoxin system reduced O2 at a rapid steady-state rate with Michaelis-Menten dependence on [adrenodoxin] (Vmax = 3.5 M e-/ min). After depletion of NADPH, reduced adrenodoxin was oxidized (auto-oxidation) with pseudo first order kinetics and the rate of e- transfer decreased ten fold. Ca2+ (&lt; 1 mM) stimulated e- leakage in both phases. The reductase-adrenodoxin-P450scc system exhibited the highest rate of leakage (Vmax = 7.8 M e- / min). At low [adrenodoxin] the majority of e- leaked through P450scc and not through adrenodoxin. In the presence of the substrate, cholesterol, leakage drastically decreased to &lt;0.5 M e- / min. These results indicate that the mitochondrial P450 systems can leak e-, producing O2 derived free radicals. Reduction of leakage during P450scc conversion of cholesterol to pregnenolone provides a clue to understanding physiological mechanisms that control e- leakage. These may include co-regulation of NADPH and cholesterol availability to the P450scc system, and a system of antioxidants for quenching the oxygen radicals.</dc:description>
  <dc:identifier>https://zenodo.org/record/890721</dc:identifier>
  <dc:identifier>10.1006/abbi.1993.1452</dc:identifier>
  <dc:identifier>oai:zenodo.org:890721</dc:identifier>
  <dc:rights>info:eu-repo/semantics/openAccess</dc:rights>
  <dc:title>Electron Leakage from the Mitochondrial NADPH-Adrenodoxin Reductase-Adrenodoxin-P450scc (Cholesterol Side Chain Cleavage) System</dc:title>
  <dc:type>info:eu-repo/semantics/article</dc:type>
  <dc:type>publication-article</dc:type>
</oai_dc:dc>
132
75
views
downloads
Views 132
Downloads 75
Data volume 72.0 MB
Unique views 129
Unique downloads 74

Share

Cite as