State 5 is the respiratory state obtained in a protocol with isolated mitochondria after a sequence of State 1 to State 4, when the concentration of O2 is depleted in the closed oxygraph chamber and zero oxygen (the anaerobic state) is reached (Chance and Williams, 1955; Table I).
State 5 is defined in the original publication in two ways: State 5 may be obtained by antimycin A treatment or by anaerobiosis (Chance and Williams, 1955; page 414). Antimycin A treatment yields a State 5 equivalent to a state for measurement of residual oxygen consumption, ROX (which may also be induced by rotenone+myxothiazol; Gnaiger 2009). Setting State 5 equivalent to ROX or anoxia (Chance and Williams 1955) can be rationalized only in the context of measurement of cytochrome redox states, whereas in the context of respiration State 5 is usually referred to as anoxic.
MitoPedia topics: EAGLE
Communicated by Gnaiger E 2011-02-27, edited 2014-04-20.
State 5 and zero oxygen
- State 5 after an aerobic-anoxic transition provides conditions for internal zero-oxygen calibration of the oxygen sensor under anoxia, which is essential for measurement of oxygen kinetics by high-resolution respirometry in a closed system (Gnaiger et al 1995; Scandurra and Gnaiger 2010). Although zero oxygen cannot strictly be reached owing to thermodynamic and kinetic contraints, a minimum pO2 of 0.0003 kPa is calculated to be reached at typical mitochondrial incubation conditions, which is due to the high mitochondrial oxygen affinitiy and is practically zero from an experimental point of view (Gnaiger et al 1995). Owing to the low oxygen affinity of permeabilized muscle fibres (Gnaiger 2003), however, State 5 is difficult to be reached in such mt-preparations within tolerable short periods of incubation time.
- Chance B, Williams GR (1955) Respiratory enzymes in oxidative phosphorylation. III. The steady state. J Biol Chem 217: 409-427.
- Gnaiger E (2003) Oxygen conformance of cellular respiration. A perspective of mitochondrial physiology. Adv Exp Med Biol 543: 39-55. »Bioblast link«
- Gnaiger E (2009) Capacity of oxidative phosphorylation in human skeletal muscle. New perspectives of mitochondrial physiology. Int J Biochem Cell Biol 41: 1837–1845. »Bioblast link«
- Gnaiger E, Steinlechner-Maran R, Méndez G, Eberl T, Margreiter R (1995) Control of mitochondrial and cellular respiration by oxygen. J Bioenerg Biomembr 27: 583-596. »Bioblast link«
- Scandurra FM, Gnaiger E (2010) Cell respiration under hypoxia: Facts and artefacts in mitochondrial oxygen kinetics. Adv Exp Med Biol 662: 7-25. »Bioblast link«