The murburn precepts for aerobic respiration and redox homeostasis

• Published in: Progress in biophysics and molecular biology Vol. 167; pp. 104 - 120
• Main Authors: Manoj, Kelath Murali, Bazhin, N.M.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.12.2021
• Subjects: Adenosine Triphosphate - metabolism; Aerobic respiration; Bioenergetics; Cell Respiration; Chemiosmosis; Energy Metabolism; Homeostasis; Murburn concept; Oxidation-Reduction; Oxidative Phosphorylation; Respiration; Thermodynamics; RCPE; CoQ; DNP; Homeostasis; pmf; FCCP; murzyme; Thermodynamics; Pi/POH; Bioenergetics; ADPOH/ADP; murzone; Chemiosmosis; DR(O)S; mXM; mOxPhos; ACP/UCP; SOD; CN; Murburn concept; IMS; IPLM/IMM; Comp. I-IV; OPLM/OMM; ADPOP/ATP; Aerobic respiration; ETC; TMP; murburn; CRAS
• ISSN: 0079-6107; 1873-1732; 1873-1732
• DOI: 10.1016/j.pbiomolbio.2021.05.010

Murburn concept is a new perspective to metabolism which posits that certain redox enzymes/proteins mediate catalysis outside their active site, via diffusible reactive oxygen species (DROS, usually deemed as toxic wastes). We have recently questioned the proton-centric chemiosmotic rotary ATP synthesis (CRAS) explanation for mitochondrial oxidative phosphorylation (mOxPhos) and proposed an oxygen-centric murburn model in lieu. Herein, the chemical equations and thermodynamic foundations for this new model of mOxPhos are detailed. Standard transformed Gibbs free energy values of respiratory reactions are calculated to address the spontaneity, control, and efficiency of oxidative phosphorylation. Unlike the deterministic/multi-molecular and ‘irreducibly complex’ CRAS model, the stochastic/bimolecular and parsimonious murburn reactions afford a more viable precept for the variable and non-integral stoichiometry, higher yield for NADH than FADH2, and origin/evolution of oxygen-centric cellular life. Also, we present tangible DROS-based explanations for the multiple roles of various reaction components, HCN > H2S order of cellular toxicity in aerobes, and explain why oxygen inhibits anaerobes. We highlight the thermodynamic significance of proton deficiency in NADH/mitochondria and link the ‘oxygen → DROS → water’ metabolic pathway to the macroscopic physiologies of ATP-synthesis, trans-membrane potential, thermogenesis, and homeostasis. We also provide arguments for the extension of the murburn bioenergetics model to life under anoxic and extreme/unique habitats. In the context of mOxPhos, our findings imply that DROS should be seen as an essential requisite for life, and not merely as pathophysiological manifestations. ∗This manuscript addresses the physico-chemical logic that powers oxygen-centered life.∗Earlier, we have demonstrated the thermodynamic non-viability of chemiosmosis.∗Also, we had proposed and supported murburn concept based paradigm of ATP-synthesis.∗Herein, the bioenergetic chemical reactions and their thermodynamic/kinetic details are given.∗Structure-function correlations and evolutionary aspects of powering routine are discussed.∗Comprehensive analyses of diverse aspects of life support murburn concept as a pillar of life.