Affordable Access

Publisher Website

On the mechanism of rotenone-insensitive reduction of quinones by mitochondrial NADH:ubiquinone reductase The high affinity binding of NAD+and NADH to the reduced enzyme form

Authors
Journal
FEBS Letters
0014-5793
Publisher
Wiley Blackwell (John Wiley & Sons)
Publication Date
Volume
284
Issue
2
Identifiers
DOI: 10.1016/0014-5793(91)80682-s
Keywords
  • Nadh:Ubiquinone Reductase
  • Electron Acceptor
  • Steady-State Kinetics
Disciplines
  • Biology

Abstract

Abstract NADH acts as an incomplete competitive inhibitor for 5,8-dioxy-1,4-naphtoquinone during its rotenone-insensitive reduction by mitochondrial NADH:ubiquinone reductase. NAD + and ADP-ribose act as incomplete mixed-type inhibitors. K i of NAD + and NADH towards quinone are about one order less than towards ferricyanide. The bimolecular rate constant of the reduction of the enzyme by NADH in the quinone reductase reaction is about 2 times less than that of ferricyanide reductase reaction. These data indicate that the reduction site of 5,8-dioxy-1,4-naphtoquinone is close to NAD +/NADH and ferricyanide binding site. It seems that during the steady-state reduction of ferricyanide and 5,8-dioxy-1,4-naphtoquinone these oxidizers react with NADH:ubiquinone reductase reduced to different extents.

There are no comments yet on this publication. Be the first to share your thoughts.