Respiratory complexes

high-resolution terminology - matching measurements at high-resolution

Respiratory complexes

Description

Respiratory complexes are membrane-bound enzymes consisting of several subunits which are involved in energy transduction of the respiratory system. The different localizations and functions of the respiratory complexes explain the architecture of the respiratory system. Respiratory complexes of the electron transfer system tansfer electrons to reduce oxygen to water in aerobic respiration, whereas the respiratory complex ATP synthase (C_V) is part of the phosphorylation system. Proton translocation couples the electron transfer system to the phosphorylation system. Membrane-spanning respiratory complexes function as proton pumps (in most mitochondria C_I, C_III, C_IV and C_V; in yeast mitochondria C_III, C_IV and C_V). Respiratory complexes bound to one side of the inner mt-membrane and C_I transfer electrons to the Q-junction which separates upstream and downstream segments of the electron transfer system. Electron transfer complexes localized to the inner face of the inner mt-membrane are C_II and C_ETF, and a respiratory complex localized to the outer face of the inner mt-membrane is C_GpDH. The 'primary complexes' (CI to CIV)comprise the machinery for transfer of electrons from NADH and succinate to oxygen as described in an extensive series of publications by the laboratory of Hatefi (see Hatefi 1962 J Biol Chem-XLII). Secondary complexes (supercomplexes) and their activities have been described to be stable at repeated freezing, thawing, dilution, centrifugation, and storage at -2O °C. The activity of supercomplexes is representative of electron transfer function in intact mitochondria activated by appropriate substrate combinations.

Abbreviation: C_i

Reference: Gnaiger 2012 MitoPathways

MitoPedia topics: Enzyme