Any electron transfer hemoprotein having a mode of action in which the transfer of a single electron is effected by a reversible valence change of the central iron atom of the heme prosthetic group between the +2 and +3 oxidation states; classified as cytochromes a in which the heme contains a formyl side chain, cytochromes b, which contain protoheme or a closely similar heme that is not covalently bound to the protein, cytochromes c in which protoheme or other heme is covalently bound to the protein, and cytochromes d in which the iron-tetrapyrrole has fewer conjugated double bonds than the hemes have. Well-known cytochromes have been numbered consecutively within groups and are designated by subscripts (beginning with no subscript), e.g. cytochromes c, c1, C2, . New cytochromes are named according to the wavelength in nanometres of the absorption maximum of the a-band of the iron (II) form in pyridine, e.g., c-555.
Haem-containing proteins; some cytochromes react with oxygen directly; others are intermediates in the oxidation of reduced coenzymes. Unlike haemoglobin, the iron in the haem of cytochromes undergoes oxidation and reduction.
Any of the complex protein respiratory pigments (enzymes) occurring within plant and animal cells. They usually occur in mitochondria, and function as electron carriers in biological oxidation. Cytochromes are involved in the “handing off” of electrons to each other in a stepwise fashion. In the process of “handing off” other events take place which result in the production of energy that the cell needs and is able to use.
Electron carriers in the respiratory chain and elsewhere. All cytochromes have a heme prosthetic group which contains iron. The iron fluctuates between the +2 and +3 states. The cytochrome P-450 enzymes are important to the detoxification processes in the body.
Iron-containing proteins found in human cells; involved in cellular metabolism.
A compound consisting of a protein linked to heme. Cytochromes act as electron transfer agents in biological oxidation-reduction reactions, particularly those associated with the mitochondria in cellular respiration.
An iron-containing protein found in the mitochondria of eukaryotic cells; each is given a letter name (a, b, c). The cytochrome transport system (electron transport chain) is the last stage in aerobic cell respiration.
Protein complexes that contain heme and operate within the electron transport chain.
A compound comprising of iron, serving as a vehicular agent for hydrogen, facilitating the eventual liberation of energy through the process of aerobic respiration.