Permeant cationic fluorescent probes are shown to be selectively accumulated by the mitochondria of living cells. Mitochondria-specific interaction of such molecules is apparently dependent on the high trans-membrane potential (inside negative) maintained by functional mitochondria. Dissipation of the mitochondrial trans-membrane and potential by ionophores or inhibitors of electron transport eliminates the selective mitochondrial association of these compounds. The application of such potential-dependent probes in conjunction with fluorescence microscopy allows the monitoring of mitochondrial membrane potential in individual living cells. Marked elevations in mitochondria-associated probe fluorescence have been observed in cells engaged in active movement. This approach to the analysis of mitochondrial membrane potential should be of value in future investigations of the control of energy metabolism and energy requirements of specific biological functions at the cellular level.

https://rupress.org/jcb/article-pdf/88/3/526/1388807/526.pdf

Monitoring of relative mitochondrial membrane potential in living cells by fluorescence microscopy.

Mitochondria are recognized as one of the most important targets for new drug design in cancer, cardiovascular, and neurological diseases. Currently, the most effective way to deliver drugs specifically to mitochondria is by covalent linking a lipophilic cation such as an alkyltriphenylphosphonium moiety to a pharmacophore of interest. Other delocalized lipophilic cations, such as rhodamine, natural and synthetic mitochondria-targeting peptides, and nanoparticle vehicles, have also been used for mitochondrial delivery of small molecules. Depending on the approach used, and the cell and mitochondrial membrane potentials, more than 1000-fold higher mitochondrial concentration can be achieved. Mitochondrial targeting has been developed to study mitochondrial physiology and dysfunction and the interaction between mitochondria and other subcellular organelles and for treatment of a variety of diseases such as neurodegeneration and cancer. In this Review, we discuss efforts to target small-molecule compounds to mitochondria for probing mitochondria function, as diagnostic tools and potential therapeutics. We describe the physicochemical basis for mitochondrial accumulation of lipophilic cations, synthetic chemistry strategies to target compounds to mitochondria, mitochondrial probes, and sensors, and examples of mitochondrial targeting of bioactive compounds. Finally, we review published attempts to apply mitochondria-targeted agents for the treatment of cancer and neurodegenerative diseases.

/pdf/mitochondria-targeted-triphenylphosphonium-based-compounds-4xqo2evab5.pdf

Mitochondria-Targeted Triphenylphosphonium-Based Compounds: Syntheses, Mechanisms of Action, and Therapeutic and Diagnostic Applications

Mitochondrial oxidative damage contributes to a wide range of pathologies, including cardiovascular disorders and neurodegenerative diseases. Therefore, protecting mitochondria from oxidative damage should be an effective therapeutic strategy. However, conventional antioxidants have limited efficacy due to the difficulty of delivering them to mitochondria in situ. To overcome this problem, we developed mitochondria-targeted antioxidants, typified by MitoQ, which comprises a lipophilic triphenylphosphonium (TPP) cation covalently attached to a ubiquinol antioxidant. Driven by the large mitochondrial membrane potential, the TPP cation concentrates MitoQ several hundred-fold within mitochondria, selectively preventing mitochondrial oxidative damage. To test whether MitoQ was active in vivo, we chose a clinically relevant form of mitochondrial oxidative damage: cardiac ischemia-reperfusion injury. Feeding MitoQ to rats significantly decreased heart dysfunction, cell death, and mitochondrial damage after ischemia-reperfusion. This protection was due to the antioxidant activity of MitoQ within mitochondria, as an untargeted antioxidant was ineffective and accumulation of the TPP cation alone gave no protection. Therefore, targeting antioxidants to mitochondria in vivo is a promising new therapeutic strategy in the wide range of human diseases such as Parkinson's disease, diabetes, and Friedreich's ataxia where mitochondrial oxidative damage underlies the pathology.

Targeting an antioxidant to mitochondria decreases cardiac ischemia-reperfusion injury

Foreword to the First Edition.Preface.Acknowledgements.Introduction.1 The Chemical Structures and Properties of Condensed Inorganic Phosphates.1.1 The Structures of Condensed Phosphates.1.1.1 Cyclophosphates.1.1.2 Polyphosphates.1.1.3 Branched Inorganic Phosphates, or 'Ultraphosphates'.1.2 Some Chemical Properties of Condensed Inorganic Polyphosphates.1.3 Physico-Chemical Properties of Condensed Inorganic Polyphosphates.2 Methods of Polyphosphate Assay in Biological Materials.2.1 Methods of Extraction from Biological Materials.2.2 Chromatographic Methods.2.3 Colorimetric and Fluorimetric Methods.2.4 Cytochemical Methods.2.5 X-Ray Energy Dispersive Analysis.2.6 31P Nuclear Magnetic Resonance Spectroscopy.2.7 Other Physical Methods.2.8 Gel Electrophoresis.2.9 Enzymatic Methods.3 The Occurrence of Polyphosphates in Living Organisms.4 The Forms in which Polyphosphates are Present in Cells.4.1 Polyphosphate-Cation Complexes.4.2 Polyphosphate-Ca2+-Polyhydroxybutyrate Complexes.4.3 Complexes of Polyphosphates with Nucleic Acids.4.4 Binding of Polyphosphates with Proteins.5 Localization of Polyphosphates in Cells of Prokaryotes and Eukaryotes.5.1 Prokaryotes.5.2 Eukaryotes.6 Enzymes of Polyphosphate Biosynthesis and Degradation.6.1 Enzymes of Polyphosphate Biosynthesis.6.1.1 Polyphosphate Kinase (Polyphosphate:ADP Phosphotransferase, EC 2.7.4.1).6.1.2 3-Phospho-D-Glyceroyl-Phosphate:Polyphosphate Phosphotransferase (EC 2.7.4.17).6.1.3 Dolichyl-Diphosphate:Polyphosphate Phosphotransferase (EC 2.7.4.20).6.2 Enzymes of Polyphosphate Degradation.6.2.1 Polyphosphate-Glucose Phosphotransferase (EC 2.7.1.63).6.2.2 NAD Kinase (ATP:NAD 2--Phosphotransferase, EC 2.7.1.23).6.2.3 Exopolyphosphatase (Polyphosphate Phosphohydrolase, EC 3.6.1.11).6.2.4 Adenosine-Tetraphosphate Phosphohydrolase (EC 3.6.1.14).6.2.5 Triphosphatase (Tripolyphosphatase, EC 3.6.1.25).6.2.6 Endopolyphosphatase (Polyphosphate Depolymerase, EC 3.6.1.10).6.2.7 PolyP:AMP Phosphotransferase.7 The Functions of Polyphosphates and Polyphosphate-Dependent Enzymes.7.1 Phosphate Reserve.7.1.1 In Prokaryotes.7.1.2 In Eukaryotes.7.2 Energy Source.7.2.1 Polyphosphates in Bioenergetics of Prokaryotes.7.2.2 Polyphosphate in Bioenergetics of Eukaryotes.7.3 Cations Sequestration and Storage.7.3.1 In Prokaryotes.7.3.2 In Eukaryotes.7.4 Participation in Membrane Transport.7.5 Cell Envelope Formation and Function.7.5.1 Polyphosphates in the Cell Envelopes of Prokaryotes.7.5.2 Polyphosphates in the Cell Envelopes of Eukaryotes.7.6 Regulation of Enzyme Activities.7.7 Gene Activity Control, Development and Stress Response.7.7.1 In Prokaryotes.7.7.2 In Lower Eukaryotes.7.8 The Functions of Polyphosphates in Higher Eukaryotes.8 The Peculiarities of Polyphosphate Metabolism in Different Organisms.8.1 Escherichia coli.8.1.1 The Dynamics of Polyphosphates under Culture Growth.8.1.2 The Effects of Pi Limitation and Excess.8.1.3 The Effects of Mutations on Polyphosphate Levels and Polyphosphate-Metabolizing Enzyme Activities.8.1.4 The Effects of Nutrition Deficiency and Environmental Stress.8.2 Pseudomonas aeruginosa.8.3 Acinetobacter.8.4 Aerobacter aerogenes (Klebsiella aerogenes).8.5 Azotobacter.8.6 Cyanobacteria (Blue-Green Algae) and other Photosynthetic Bacteria.8.7 Mycobacteria and Corynebacteria.8.8 Propionibacteria.8.9 Archae.8.10 Yeast.8.10.1 Yeast Cells Possess Different Polyphosphate Fractions.8.10.2 The Dynamics of PolyP Fractions during the Cell Cycle.8.10.3 The Relationship between the Metabolism of Polyphosphates and other Compounds.8.10.4 Polyphosphate Fractions at Growth on a Pi-Sufficient Medium with Glucose.8.10.5 The Effects of Pi Limitation and Excess.8.10.6 The Effects of other Conditions on the Polyphosphate Content in Yeast Cells.8.10.7 The Effects of Inhibitors on the Polyphosphate Content in Yeast Cells.8.10.8 The Effects of Mutations on the Content and Chain Lengths of Polyphosphate in Yeast.8.11 Other Fungi (Mould and Mushrooms).8.12 Algae.8.12.1 Localization and Forms in Cells.8.12.2 The Dynamics of Polyphosphates in the Course of Growth.8.12.3 The Influence of Light and Darkness.8.12.4 The Effects of Pi Limitation and Excess.8.12.5 Changes in Polyphosphate Content under Stress Conditions.8.13 Protozoa.8.14 Higher Plants.8.15 Animals.9 Applied Aspects of Polyphosphate Biochemistry.9.1 Bioremediation of the Environment.9.1.1 Enhanced Biological Phosphate Removal.9.1.2 Removal of Heavy Metals from Waste.9.2 Polyphosphates and Polyphosphate-Metabolizing Enzymes in Assay and Synthesis.9.3 Polyphosphates in Medicine.9.3.1 Antiseptic and Antiviral Agents.9.3.2 Polyphosphate Kinase as a Promising Antimicrobial Target.9.3.3 Polyphosphates as New Biomaterials.9.3.4 Polyphosphates in Bone Therapy and Stomathology.9.4 Polyphosphates in Agriculture.9.5 Polyphosphates in the Food Industry.10 Inorganic Polyphosphates in Chemical and Biological Evolution.10.1 Abiogenic Synthesis of Polyphosphates and Pyrophosphate.10.2 Phosphorus Compounds in Chemical Evolution.10.3 Polyphosphates and Pyrophosphates: Fossil Biochemical Reactions and the Course of Bioenergetic Evolution.10.4 Changes in the Role of Polyphosphates in Organisms at Different Evolutionary Stages.References.Index of Generic Names.Subject Index.

The biochemistry of inorganic polyphosphates

Optical measurement of membrane potential is a new tool for physiologists and has already found many applications. However, the number of possible pitfalls is alarming, particularly in situations where comparison with electrode measurements is impossible. Exhaustive and elaborate controls are clearly necessary; and yet they never provide complete assurance that an optical signal represents a change in membrane potential. In our opinion, the use of redistribution signals, which are slower, and thus more likely to represent to secondary effects of changes in membrane potential, and require permeant dyes with access to the internal millieu, may be more hazardous than the use of either fast or intrinsic signals. However, the larger size of the redistribution signals has endowed them with obvious appeal. If more sensitive fast signals can be found, the use of this kind of signal would be facilitated.

Optical measurement of membrane potential.

Conversion of biomembrane-produced energy into electric form. I. Submitochondrial particles.

Conversion of biomembrane-produced energy into electric form. III. Chromatophores of Rhodospirillum rubrum

Ability of mitochondria and submitochondrial particles (SMP) to generate a membrane potential on the addition of unpenetrating electron donors and acceptors and trimethylhydroquinone was used for specification of organization of the electron transfer chain. Ferri- and ferrocyanide added to mitochondria induce the membrane potential generation exchanging electrons only with cytochromes c or c1. Ferricyanide added to SMP induces the membrane potential taking electrons in three places: from NAD-H dehydrogenase, succinate dehydrogenase and in the presence of antimicyne A from cytochrome beta region. The difference of two sides of mitochondrial membrane is in agreement with the chemielectric hypothesis. According to this hypothesis protons from internal part of mitochondria are taken up to input H+-channel after electrons. That is why electrons come near the inner surface of the membrane and can be transferred from respiratory chain to water soluble acceptors. In output channels protons move under the action of intramembrane electrostatic field and in the direction of rising polarization of the medium. Protons are released to output channels while electrons are transferred to next carrier within the hydrophobic part of the membrane far from external surface of the membrane and cannot be transferred to water soluble acceptors.

Potential difference across the membrane of subcellular particles. IV. Study of the part of the respiratory chain from FAD to cytochrome c by the ion penetration technic

[Photoinduced absorption of hydrophobic penetrating anions by Rhodospirillum rubrum non-sulfur purple bacteria].

Transformation of light energy, of substrate oxidation and ATP hydrolysis energy into electric form during both oxidative and photo-phosphorylation can be described not only by means of chemiosmotic but also by chemielectric hypothesis. The latter hypothesis supposes, that dehydrated protons are taken up by electrostatic forces into the inner part of the membrane. Protons move into the input channels following electrons driven by chemical forces. Inside the membrane H+-ions are released into the output channels when electrons are transferred to the next electron carriers. Output H+-channels eject protons towards the other side of the membrane along the gradient of rising polarization of the channels. The inner resistance of chemielectric potential generators is lower than that of chemiosmotic one. A model of chemielectric mechanism is proposed. According to this mechanism electrons driving protons move along nonheme iron proteins and H+-ions are released into the output channels from semiquinones and hydroquinones.

Tsofina Lm

Papers

Conversion of biomembrane-produced energy into electric form. I. Submitochondrial particles.

Conversion of biomembrane-produced energy into electric form. III. Chromatophores of Rhodospirillum rubrum

Potential difference across the membrane of subcellular particles. IV. Study of the part of the respiratory chain from FAD to cytochrome c by the ion penetration technic

[Photoinduced absorption of hydrophobic penetrating anions by Rhodospirillum rubrum non-sulfur purple bacteria].

Potential difference across subcellular particle membranes. I. Chemiosmotic and chemielectric mechanism of generation