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Med Hypotheses. 2013 Oct;81(4):587-91. doi: 10.1016/j.mehy.2013.07.008. Epub 2013 Jul 30.

Does menaquinone participate in brain astrocyte electron transport?

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BioMérieux, 100 Rodolphe Dr., Durham, NC 27712, United States.


Quinone compounds act as membrane resident carriers of electrons between components of the electron transport chain in the periplasmic space of prokaryotes and in the mitochondria of eukaryotes. Vitamin K is a quinone compound in the human body in a storage form as menaquinone (MK); distribution includes regulated amounts in mitochondrial membranes. The human brain, which has low amounts of typical vitamin K dependent function (e.g., gamma carboxylase) has relatively high levels of MK, and different regions of brain have different amounts. Coenzyme Q (Q), is a quinone synthesized de novo, and the levels of synthesis decline with age. The levels of MK are dependent on dietary intake and generally increase with age. MK has a characterized role in the transfer of electrons to fumarate in prokaryotes. A newly recognized fumarate cycle has been identified in brain astrocytes. The MK precursor menadione has been shown to donate electrons directly to mitochondrial complex III.


Vitamin K compounds function in the electron transport chain of human brain astrocytes.

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