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Fig. 1 | Journal of Cardiothoracic Surgery

Fig. 1

From: Myocardial insufficiency is related to reduced subunit 4 content of cytochrome c oxidase

Fig. 1

Mitochondrial electron transport chain (ETC) is composed of four multisubunit respiratory complexes and the carrier proteins that together perform mitochondrial respiration. Electrons are delivered from NADH and FADH2 to complex I and complex II, respectively, and subsequently passed through the electron transport chain to the final acceptor i.e. molecular oxygen to form water. This transfer of electrons through the ETC is associate with the translocation of protons at complexes I, III and IV across the mitochondrial membrane into the intermembrane space, thus trapping the energy in the form of electrochemical gradient., This energy stored in the gradient is used to perform oxidative phosphorylation i.e. formation of ATP by ATP synthase (complex V). Energy supply is closely related to the energy demand of the cell. Higher myocardial workload results in increased contractility spending more ATP and consuming more oxygen. Depending on the H+/e -stoichiometry and different efficiency of ATP synthesis, two different states of respiration (relaxed/active) may be considered [1,2,3]. A schematic representation of the enzymes involved in mitochondrial respiration and oxidative phosphorylation. Models of protein crystal structures were taken from the Protein Data Bank ( The corresponding PDB IDs’ for complex I to V were: 2FUG, 1YQ3, INTZ, 10CC and 101

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