Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, 422 Curie Blvd, Philadelphia, PA 19104, USA.
Int J Mol Sci. 2022 May 16;23(10):5550. doi: 10.3390/ijms23105550.
Maintaining a robust, stable source of energy for doing chemical and physical work is essential to all living organisms. In eukaryotes, metabolic energy (ATP) production and consumption occurs in two separate compartments, the mitochondrial matrix and the cytosol. As a result, understanding eukaryotic metabolism requires knowledge of energy metabolism in each compartment and how metabolism in the two compartments is coordinated. Central to energy metabolism is the adenylate energy state ([ATP]/[ADP][Pi]). ATP is synthesized by oxidative phosphorylation (mitochondrial matrix) and glycolysis (cytosol) and each compartment provides the energy to do physical work and to drive energetically unfavorable chemical syntheses. The energy state in the cytoplasmic compartment has been established by analysis of near equilibrium metabolic reactions localized in that compartment. In the present paper, analysis is presented for energy-dependent reactions localized in the mitochondrial matrix using data obtained from both isolated mitochondria and intact tissues. It is concluded that the energy state ([ATP]/[ADP][Pi]) in the mitochondrial matrix, calculated from the free (unbound) concentrations, is not different from the energy state in the cytoplasm. Corollaries are: (1) ADP in both the cytosol and matrix is selectively bound and the free concentrations are much lower than the total measured concentrations; and (2) under physiological conditions, the adenylate energy states in the mitochondrial matrix and cytoplasm are not substantially different.
为进行化学和物理工作而维持强大、稳定的能量供应，是所有生物体必不可少的。在真核生物中，代谢能量（ATP）的产生和消耗发生在两个不同的隔室中，即线粒体基质和细胞质。因此，要了解真核生物的代谢，就需要了解每个隔室中的能量代谢，以及这两个隔室中的代谢是如何协调的。代谢的核心是腺苷酸能量状态（[ATP]/[ADP][Pi]）。ATP 通过氧化磷酸化（线粒体基质）和糖酵解（细胞质）合成，每个隔室都为进行物理工作和驱动能量不利的化学合成提供能量。细胞质隔室的能量状态是通过对该隔室中局部的近平衡代谢反应进行分析而确定的。在本文中，使用从分离的线粒体和完整组织中获得的数据，对定位于线粒体基质中的能量依赖反应进行了分析。结果表明，从游离（未结合）浓度计算得到的线粒体基质中的能量状态（[ATP]/[ADP][Pi]）与细胞质中的能量状态没有差异。推论是：（1）细胞质和线粒体基质中的 ADP 都是选择性结合的，游离浓度远低于总测量浓度；（2）在生理条件下，线粒体基质和细胞质中的腺苷酸能量状态没有显著差异。
