A Note on the Consequences of a Hot Mitochondrion: Some Recent Developments and Open Questions

  • Peyman Fahimi Department of Chemistry and Physics, Mount Saint Vincent University, Halifax, Nova Scotia, Canada B3M2J6; Département de chimie, Université Laval, Québec, Québec, Canada G1V 0A6
  • Mohamed A. Nasr Department of Chemistry and Physics, Mount Saint Vincent University, Halifax, Nova Scotia, Canada B3M2J6; Center of Excellence for Stem Cells and Regenerative Medicine (CESC), Zewail City of Science and Technology, 6th of October City 12588, Egypt
  • Lazaro M. A. Castanedo Department of Chemistry and Physics, Mount Saint Vincent University, Halifax, Nova Scotia, Canada B3M2J6; Department of Chemistry, Saint Mary's University, Halifax, Nova Scotia, Canada B3H3C3
  • Youji Cheng Department of Chemistry and Physics, Mount Saint Vincent University, Halifax, Nova Scotia, Canada B3M2J6; Department of Chemistry, Saint Mary's University, Halifax, Nova Scotia, Canada B3H3C3
  • Cyrus Ahmady Toussi Department of Chemistry and Physics, Mount Saint Vincent University, Halifax, Nova Scotia, Canada B3M2J6; Department of Biomedical Engineering, Hakim Sabzevari University, Sabzevar, Iran
  • Cherif Farid Matta Department of Chemistry and Physics, Mount Saint Vincent University, Halifax, Nova Scotia, Canada B3M2J6; https://orcid.org/0000-0001-8397-5353
Keywords: hot mitochondrion, mitochondrial biophysics, ATP synthase, Maxwell demon, chemiosmotic theory

Abstract

Background: Chrétien and co-workers (PLOS Biology. 2018;16(1):e2003992) recently suggested that the mitochondrion might possibly be hotter than its surrounding (by as much as 10°C).

Objectives: To examine the validity of this claim and review the possible implications and repercussion of such a claim – if true – on some aspects of mitochondrial biochemistry and biophysics.

Results: Both the chemical gradient and the electrical gradient Gibbs energy terms in the central equation of chemiosmotic theory are temperature dependent, the first explicitly and the second implicitly. A hotter mitochondrion – as claimed – would imply a 3% correction in the chemical gradient term, but we cannot estimate the corresponding effect on the electrical term at this time since the functional dependence of the voltage on the temperature is not known to the best of the authors’ knowledge. Further, if this claim is true and to the extent claimed (10°C), this may imply some heat-engine character for mitochondrial thermodynamic operation albeit this may only represent 4% at most.

Conclusions: Doubts and criticisms regarding the suggestion of a hotter mitochondrion have been raised and are briefly discussed. These doubts are contrasted with some data and considerations that support the claim of a hotter mitochondrion. It is concluded that the mitochondrion is probably hotter than its environment but not to the extent claimed by Chrétien et al. and that the thermodynamic efficiency and the mode of operation of the mitochondrion as an electrochemical battery are very slightly perturbed by even the maximum claimed revision of the temperature of its operation.

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Author Biography

Cherif Farid Matta, Department of Chemistry and Physics, Mount Saint Vincent University, Halifax, Nova Scotia, Canada B3M2J6;

Department of Chemistry and Physics, Mount Saint Vincent University, Halifax, Nova Scotia, Canada B3M2J6; Département de chimie, Université Laval, Québec, Québec, Canada G1V 0A6; Center of Excellence for Stem Cells and Regenerative Medicine (CESC), Zewail City of Science and Technology, 6th of October City 12588, Egypt; Department of Chemistry, Saint Mary's University, Halifax, Nova Scotia, Canada B3H3C3; Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, Canada B3H4J3

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Published
2020-05-02
Cited
How to Cite
Fahimi, P., Nasr, M. A., Castanedo, L. M. A., Cheng, Y., Toussi, C. A., & Matta, C. F. (2020). A Note on the Consequences of a Hot Mitochondrion: Some Recent Developments and Open Questions. Biophysical Bulletin, (43), 14-21. https://doi.org/10.26565/2075-3810-2020-43-02
Section
Cell biophysics