What is Cytochrome?
[[Image:Cytochrome c.png|thumb|250px|Cytochrome ''c'' with heme ''c''.]] '''Cytochromes''' are [[haemoprotein]]s (or [[proteins]] containing [[haem]] groups). They make [[Adenosine triphosphate|ATP]] by [[electron transport]]. They are found either as single (monomeric) proteins (e.g., [[cytochrome c]]) or as part of bigger [[enzyme]] complexes which [[catalysis|catalyze]] [[redox]] reactions. The haem group does the redox reactions. These include all chemical reactions in which atoms have their [[oxidation]] state changed. In general, redox reactions involve the transfer of [[electrons]]. == History == Cytochromes were described in 1884 as [[respiratory pigment]]s. They include ([[haemoglobin]], [[myoglobin]], [[haemocyanin]], [[haemoerythrin]] and [[chlorocruorin]].<ref>A respiratory pigment increases the oxygen-carrying ability of the blood.</ref><ref name=MacMunn>{{cite journal | doi = 10.1098/rstl.1886.0007 | jstor = 109482 | pages = 267–298 | author1 = MacMunn C.A. | title = Researches on myohaematin and the histohaematins | journal = Philosophical Transactions of the Royal Society of London | volume = 177 | publisher = The Royal Society | year = 1886| s2cid = 110335335 }}</ref> In the 1920s, [[David Keilin|Keilin]] rediscovered these respiratory pigments. He called them the cytochromes, or “cellular pigments”, and classified them as haem proteins. == Types == Several kinds of cytochrome exist and can be distinguished by [[spectroscopy]]. Three types of cytochrome are distinguished by their prosthetic groups.<ref>Prosthetic group = add-on bit which makes it work</ref> In [[mitochondrion|mitochondria]] and [[chloroplast]]s, these cytochromes are often combined in electron transport and related [[metabolism|metabolic pathways]]. == References == {{reflist}} [[Category:Iron compounds]] [[Category:Organometallic chemistry]]