BioMérieux, 100 Rodolphe Dr., Durham, NC 27712, United States.
Med Hypotheses. 2013 Oct;81(4):587-91. doi: 10.1016/j.mehy.2013.07.008. Epub 2013 Jul 30.
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.
醌类化合物在原核生物的周质空间和真核生物的线粒体中电子传递链的组件之间作为电子的膜驻留载体起作用。维生素 K 是人体中醌类化合物的一种储存形式，即甲萘醌 (MK)；分布包括在线粒体膜中有调节数量的分布。人脑具有低水平的典型维生素 K 依赖性功能（例如，γ羧化酶），但 MK 水平相对较高，而且大脑的不同区域具有不同的含量。辅酶 Q（Q）是一种从头合成的醌，其合成水平随年龄的增长而下降。MK 的水平取决于饮食摄入，并且通常随年龄增长而增加。MK 在原核生物中将电子转移到富马酸盐方面具有特征性作用。在脑星形胶质细胞中已经确定了一个新识别的富马酸循环。已经表明 MK 的前体甲萘醌可将电子直接捐赠给线粒体复合物 III。
维生素 K 化合物在人脑星形胶质细胞的电子传递链中起作用。
