In the present review, which is aimed at researchers, teachers and students in life sciences, we try to show how the physicochemical properties of the elements and molecules define the concept of redox balance. Living organism are open systems traversed by fluxes of energy and matter. During catabolic oxidative metabolism, matter—mostly hydrogenated organic molecules—is oxidized and ultimately released as CO₂. Electrons are passed over to coupling molecules, such as NAD+ and FAD, whose reduced forms serve as electrons donors in anabolic reactions. Early photosynthetic activity led to the accumulation of O₂ and the transformation of the reduction to an oxidizing atmosphere, favoring the development of oxidative metabolism in living organisms. We focus on the specific properties of O₂ that provide the chemical energy for the combustion reactions occurring in living cells. We explain the concepts of redox potential and redox balance in complex systems such as living cells, we present the main redox couples involved in cellular redox balance and we discuss the chemical properties underlying their cellular roles and, in particular, their antioxidant properties in the defense against reactive oxygen species (ROS). Finally, we try to provide an integrative view emphasizing the interplay between metabolism, oxidative stress and metabolic compartmentation in mammalian cells.

中文翻译：

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细胞氧化还原平衡中核苷酸、硫醇和 O2 的减少：生物化学家的观点

在这篇针对生命科学领域的研究人员、教师和学生的综述中，我们试图展示元素和分子的物理化学性质如何定义氧化还原平衡的概念。活的有机体是能量和物质流穿过的开放系统。在分解代谢的氧化代谢过程中，物质（主要是氢化有机分子）被氧化并最终以 CO ₂的形式释放。电子传递给耦合分子，例如 NAD+ 和 FAD，它们的还原形式在合成代谢反应中充当电子供体。早期的光合作用导致O ₂的积累和还原转变为氧化气氛，有利于生物体内氧化代谢的发展。我们专注于 O 的特定属性₂为活细胞中发生的燃烧反应提供化学能。我们解释了复杂系统（如活细胞）中氧化还原电位和氧化还原平衡的概念，我们介绍了参与细胞氧化还原平衡的主要氧化还原对，并讨论了它们在细胞作用中的化学特性，特别是它们在防御中的抗氧化特性抗活性氧（ROS）。最后，我们试图提供一个综合观点，强调哺乳动物细胞中代谢、氧化应激和代谢区室之间的相互作用。