Difference between revisions of "Mitochondrial marker"

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Mitochondrial marker

Description

Mitochondrial markers are structural or functional properties that are specific for mitochondria. In isolated mitochondria, protein can be determined as a measure of amount of mitochondria or mt-concentration [mg mt-protein/ml]. However, protein cannot be used as a mt-biomarker in other mitochondrial preparations. A structural mt-marker is the area of the inner mt-membrane or mt-volume determined stereologically, which has its limitations due to different states of swelling. If mt-area is determined by electron microscopy, the statistical challenge has to be met to convert area into a volume. When fluorescent dyes are used as mt-marker, distinction is necessary between mt-membrane potential dependent and independent dyes. mtDNA or cardiolipin content may be considered as a mt-marker. Determination of mitochondrial marker enzymes may be molecular (amount of protein) or functional (enzyme activities). Respiratory capacity in a defined respiratory state of a mt-preparation can be considered as a functional mt-marker, in which case respiration is expressed as flux control ratios.

Abbreviation: mt-marker

Reference: Gnaiger 2014 MitoPathways

MitoPedia methods: Respirometry

Biomarkers

Markers for size are volume, mass, area. If mass is not expressed as total mass but as protein mass, then a physical marker of size is replaced by a biochemical marker. Determination of the size of a system under investigation always requires definition of the system. The system (subject) whose phenotype is studied may be an organism, a tissue or a cell. The biochemical marker total protein can be replaced by a specific protein, e.g. by a marker enzyme. A biomarker can be considered as a functional element. Expressing performance (I_O2, oxygen flow per biological system) per size yields specific performance (J_O2, oxygen flux = flow per system size) in an unstructured analysis. A biomarker introduces a structural (and functional) element into the analysis. Therefore, expressing performance (I_O2) per functional element (biomarker) yields marker-specific performance (J_mt,O2, mt-specific oxygen flux = flow per mt-marker) in a structured analysis.

When replacing an enzyme activity by the respiratory activity in a defined respiratory state as a biomarker, then flow per mt-marker becomes a flux control ratio (FCR). Expressing structure by functional markers is without problem as long as the structure in question does not undergo any functional (qualitative) changes.

Respiratory performance capacity of an organism, tissue or cell may change due to a change in size, concentration of functional elements (biomarker density) or element function (mt-specific function).

References

>> O2k-Protocols: mitochondrial and marker-enzymes

Gnaiger E (2009) Capacity of oxidative phosphorylation in human skeletal muscle. New perspectives of mitochondrial physiology. Int J Biochem Cell Biol 41: 1837-45. »PMID: 19467914
Larsen 2012 J Physiol
Pesta D, Hoppel F, Macek C, Messner H, Faulhaber M, Kobel C, Parson W, Burtscher M, Schocke M, Gnaiger E (2011) Similar qualitative and quantitative changes of mitochondrial respiration following strength and endurance training in normoxia and hypoxia in sedentary humans. Am J Physiol Regul Integr Comp Physiol 301: R1078–87. »Open Access

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+== Biomarkers ==
+Markers for '''size''' are volume, mass, area. If mass is not expressed as total mass but as protein mass, then a physical marker of size is replaced by a biochemical marker. Determination of the size of a system under investigation always requires definition of the system. The system (subject) whose phenotype is studied may be an organism, a tissue or a cell. The biochemical marker total protein can be replaced by a specific protein, e.g. by a marker enzyme. A biomarker can be considered as a functional element. Expressing performance (''I''<sub>O2</sub>, oxygen flow per biological system) per size yields specific performance (''J''<sub>O2</sub>, oxygen flux = flow per system size) in an unstructured analysis. A biomarker introduces a structural (and functional) element into the analysis. Therefore, expressing performance (''I''<sub>O2</sub>) per functional element (biomarker) yields marker-specific performance (''J''<sub>mt,O2</sub>, mt-specific oxygen flux = flow per mt-marker) in a structured analysis.
+When replacing an enzyme activity by the respiratory activity in a defined respiratory state as a biomarker, then flow per mt-marker becomes a flux control ratio (''FCR''). Expressing structure by functional markers is without problem as long as the structure in question does not undergo any functional (qualitative) changes.
+Respiratory performance capacity of an organism, tissue or cell may change due to a change in size, concentration of functional elements (biomarker density) or element function (mt-specific function).
 == References ==