NextGen-O2k Instrument

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NextGen-O2k Instrument

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NextGen-O2k Instrument


MitoPedia: NextGen-O2k

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TermAbbreviationDescription
ChlororespirationChlororespiration is the phenomenon by which oxygen is consumed by a putative respiratory electron transfer chain (ETC) within the thylakoid membrane of the chloroplasts and ATP is produced. It is a process that involves the interaction with the photosynthetic ETC in which the NAD(P)H dehydrogenase enzyme transfers electrons to oxygen molecules with the assistance of the photosynthetic Plastoquinone (PQ), which acts as a non-photochemical redox carrier. Initially described in the unicellular alga Chlamydomonas reindhartdii, chlororespiration was highly disputed for years until the discovery of a NAD(P)H-dehydrogenase (Ndh) complex (plastidic encoded) and plastid terminal oxidase (PTOX) (nuclear encoded) in higher-plant chloroplasts. The PTOX, which is homologous to the plant mitochondrial alternative oxidase, has the role of preventing the over-reduction of the PQ pool while the Ndh complexes provide a gateway for the electrons to form the ETC and consume oxygen. As a result of this process there is a cyclic electron flow around the Photosystem I (PSI) that has been reported to be activated under stress conditions acting as a photoprotection mechanism and could be involved in protecting against any other stress that implies the increase of ROS formation.
Hydrogen peroxideH2O2
Hydrogen peroxide
Hydrogen peroxide, H2O2 or dihydrogen dioxide, is one of several reactive oxygen intermediates generally referred to as reactive oxygen species (ROS). It is formed in various enzyme-catalyzed reactions (e.g., superoxide dismutase) with the potential to damage cellular molecules and structures. H2O2 is dismutated by catalase to water and oxygen. H2O2 is produced as a signaling molecule in aerobic metabolism and passes membranes more easily compared to other ROS.
Mitochondrial membrane potentialmtMP, Δψ [V]The mitochondrial membrane potential, mtMP, is the electric part of the protonmotive force, ΔpH+.

Δψ = ΔpH+ - ΔµH+ / F

mtMP or Δψ is the potential difference across the inner mitochondrial (mt) membrane, expressed in the electric unit of volt [V]. Electric force of the mitochondrial membrane potential is the electric energy change per ‘motive’ electron or per electron moved across the transmembrane potential difference, with the number of ‘motive’ electrons expressed in the unit coulomb [C].
NextGen-O2k
NextGen-O2k InstrumentNextGen-O2k Instrument
NextGen-O2k Technical developments
Oxygen kineticsOxygen kinetics describes the dependence of respiration of isolated mitochondria or cells on oxygen partial pressure. Frequently, a strictly hyperbolic kinetics is observed, with two parameters, the oxygen pressure at half-maximum flux, p50, and maximum flux, Jmax. The p50 is in the range of 0.2 to 0.8 kPa for cytochrome c oxidase, isolated mitochondria and small cells, strongly dependent on Jmax and coupling state.
PhotoBiologyPBPhotoBiology is the scientific study of the beneficial or harmful effects of light, understood as non-ionizing radiation (i.e. ultraviolet, visible and infrared radiation) on living organisms. It includes topics such as the study of photosynthesis, photochemistry, photophysics, photomorphogenesis, vision, bioluminescence, circadian rhythms and photodynamic therapy. Non-ionizing (or non-ionising) radiation is any type of electromagnetic radiation that does not carry enough energy per quantum (photon energy below 10 eV) to completely remove an electron from an atom or molecule. When photons contact molecules, the molecules can absorb the photon energy and become excited, reacting with surrounding molecules and stimulating "photochemical" and "photophysical" changes.
PhotosynthesisPSPhotosynthesis is the process used by plants and other organisms that converts light (mostly solar) energy into chemical energy which is subsequently released to fuel organisms' activities. It has two phases: the light-dependent phase and the light-independent (dark) phase. In plants, algae, and cynobacteria, light energy is absorbed during the light phase by the pigment called Chlorophyll and used to split water and generate short-term stores of chemical energy - adenosine triphosphate (ATP), and reducing power - nicotinamide adenine dinucleotide phosphate (NADPH), with the net production of O2 gas as a waste product. And during the dark phase this chemical energy and reducing power are used to synthesize organic matter from the atmospheric CO2 in the form of carbohydrates or sugars through the metabolic pathway called Calvin cycle. The whole process is what is called oxygenic photosynthesis and is responsible for producing and maintaining the oxygen concentration of the Earth’s atmosphere. In bacteria such as the cyanobacteria photosynthesis involves the plasma membrane and the cytoplasm, and in Eukaryotic cells (plants and algae) photosynthesis takes place inside organelles called chloroplasts.
Q redox stateQQ redox state
Q-SensorQ-Sensor has been designed as a part of the Q-Module for detection of Cyclic voltammetry and the Q-redox state. The Q-Stopper with the reference electrode is called Q-Sensor which is plugged in the NextGen-O2k. In order to detect the Q-redox ratio , a three-electrode system is used. Two (glassy carbon and platinum electrode) out of the three electrodes are built in the Q-Stopper, while the reference electrode is movable.
Three-electrode systemThree-electrode system is the three-electrode setup of the Q-Sensor. In general it is applied in voltammetry to study the current as a function of the applied potential with three different electrodes: 1.) working electrode which makes contact with analyte, 2.) reference electrode which has a known potential and controls the current of the working electrode, but it does not pass any current, and 3.) counter electrode which maintains a constant potential while passing current to counter redox events at the working electrode. In the Q-Sensor, which is and integral part of the Q-Module, the working or detecting electrode is a glassy carbon (GC) electrode which is set to a given potential versus a silver/silver chloride (Ag/AgCl) reference electrode. The applied potential on the surface of the GC should be sufficient to either oxidise reduced analyte (in our case Coenzyme Q) or to reduce oxidised CoQ. The third electrode is a platinum electrode (Pt) that acts as a counter electrode to complete the circuit that is rate-limited by electron transfer on the GC. To determine the Q redox ratio the GC electrode is set at the oxidation peak potential.


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