Electron transfer kinetics of the mitochondrial outer membrane protein mitoNEET.

Electron transfer kinetics of the mitochondrial outer membrane protein mitoNEET.
Free Radic Biol Med. 2018 Apr 25;:
Authors: Li X, Wang Y, Tan G, Lyu J, Ding H
Abstract
Increasing evidence suggests that the mitochondrial outer membrane protein mitoNEET is a key regulator of energy metabolism, iron homeostasis, and production of reactive oxygen species in mitochondria. Previously, we reported that mitoNEET is a redox enzyme that catalyzes electron transfer from the reduced flavin mononucleotide (FMNH2) to oxygen or ubiquinone via its unique [2Fe-2S] clusters. Here, we explore the reduction and oxidation kinetics of the mitoNEET [2Fe-2S] clusters under anaerobic and aerobic conditions. We find that the mitoNEET [2Fe-2S] clusters are rapidly reduced by a catalytic amount of FMNH2 which is reduced by flavin reductase and an equivalent amount of NADH under anaerobic conditions. When the reduced mitoNEET [2Fe-2S] clusters are exposed to air, the [2Fe-2S] clusters are slowly oxidized by oxygen at a rate constant of about 6.0M-1s-1. Compared with oxygen, ubiquinone-2 has a much higher activity to oxidize the pre-reduced mitoNEET [2Fe-2S] clusters at a rate constant of about 3.0×103 M-1s-1 under anaerobic conditions. Under aerobic conditions, the mitoNEET [2Fe-2S] clusters can still be reduced by FMNH2 in the presence of flavin reductase and excess NADH. However, when NADH is completely consumed, the reduced mitoNEET [2Fe-2S] clusters are gr...

Source: Free Radical Biology and Medicine - April 25, 2018 Category: Biology Authors: Li X, Wang Y, Tan G, Lyu J, Ding H Tags: Free Radic Biol Med Source Type: research