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氧化磷酸化的一种简单水力模拟模型。

A Simple Hydraulic Analog Model of Oxidative Phosphorylation.

作者信息

Willis Wayne T, Jackman Matthew R, Messer Jeffrey I, Kuzmiak-Glancy Sarah, Glancy Brian

机构信息

1Center for Metabolic and Vascular Biology, Arizona State University at Mayo Clinic, Scottsdale, AZ; 2Division of Endocrinology, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO; 3Exercise Science Department, Mesa Community College, Mesa, AZ; 4Department of Biomedical Engineering, The George Washington University, Washington, DC; and 5Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD.

出版信息

Med Sci Sports Exerc. 2016 Jun;48(6):990-1000. doi: 10.1249/MSS.0000000000000884.

Abstract

Mitochondrial oxidative phosphorylation is the primary source of cellular energy transduction in mammals. This energy conversion involves dozens of enzymatic reactions, energetic intermediates, and the dynamic interactions among them. With the goal of providing greater insight into the complex thermodynamics and kinetics ("thermokinetics") of mitochondrial energy transduction, a simple hydraulic analog model of oxidative phosphorylation is presented. In the hydraulic model, water tanks represent the forward and back "pressures" exerted by thermodynamic driving forces: the matrix redox potential (ΔGredox), the electrochemical potential for protons across the mitochondrial inner membrane (ΔGH), and the free energy of adenosine 5'-triphosphate (ATP) (ΔGATP). Net water flow proceeds from tanks with higher water pressure to tanks with lower pressure through "enzyme pipes" whose diameters represent the conductances (effective activities) of the proteins that catalyze the energy transfer. These enzyme pipes include the reactions of dehydrogenase enzymes, the electron transport chain (ETC), and the combined action of ATP synthase plus the ATP-adenosine 5'-diphosphate exchanger that spans the inner membrane. In addition, reactive oxygen species production is included in the model as a leak that is driven out of the ETC pipe by high pressure (high ΔGredox) and a proton leak dependent on the ΔGH for both its driving force and the conductance of the leak pathway. Model water pressures and flows are shown to simulate thermodynamic forces and metabolic fluxes that have been experimentally observed in mammalian skeletal muscle in response to acute exercise, chronic endurance training, and reduced substrate availability, as well as account for the thermokinetic behavior of mitochondria from fast- and slow-twitch skeletal muscle and the metabolic capacitance of the creatine kinase reaction.

摘要

线粒体氧化磷酸化是哺乳动物细胞能量转导的主要来源。这种能量转换涉及数十种酶促反应、高能中间体以及它们之间的动态相互作用。为了更深入地了解线粒体能量转导的复杂热力学和动力学(“热动力学”),本文提出了一种简单的氧化磷酸化水力模拟模型。在该水力模型中,水箱代表由热力学驱动力施加的正向和反向“压力”:线粒体基质氧化还原电位(ΔGredox)、线粒体内膜两侧质子的电化学电位(ΔGH)以及腺苷5'-三磷酸(ATP)的自由能(ΔGATP)。净水流从水压较高的水箱通过“酶管道”流向水压较低的水箱,这些管道的直径代表催化能量转移的蛋白质的电导(有效活性)。这些酶管道包括脱氢酶反应、电子传递链(ETC)以及ATP合酶与跨越内膜的ATP - 腺苷5'-二磷酸交换体的联合作用。此外,模型中还包括活性氧的产生,它被视为一种泄漏,由高压(高ΔGredox)从ETC管道中驱出,并且质子泄漏的驱动力和泄漏途径的电导都依赖于ΔGH。模型中的水压和水流被证明能够模拟在急性运动、慢性耐力训练以及底物可用性降低的情况下,在哺乳动物骨骼肌中实验观察到的热力学力和代谢通量,同时还能解释快肌和慢肌骨骼肌中线粒体的热动力学行为以及肌酸激酶反应的代谢容量。

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