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Complex IV contains a cytochrome a/a3-domain that transfers electrons and catalyzes the reaction of oxygen to water. Photosystem II, the first protein complex in the light-dependent reactions of oxygenic photosynthesis, contains a cytochrome b subunit. Cyclooxygenase 2, an enzyme involved in inflammation, is a cytochrome b protein.
The cytochrome complex, or cyt c, is a small hemeprotein found loosely associated with the inner membrane of the mitochondrion where it plays a critical role in cellular respiration. It transfers electrons between Complexes III (Coenzyme Q – Cyt c reductase) and IV (Cyt c oxidase). Cytochrome c is highly water-soluble, unlike other cytochromes.
Small soluble cytochrome c proteins with a molecular weight of 8-12 kDa and a single heme group belong to class I. [10] [11] It includes the low-spin soluble cytC of mitochondria and bacteria, with the heme-attachment site located towards the N-terminus, and the sixth ligand provided by a methionine residue about 40 residues further on towards the C-terminus.
Both are proton pumps that produce a transmembrane proton gradient. In fact, cytochrome b 6 and subunit IV are homologous to mitochondrial cytochrome b [5] and the Rieske iron-sulfur proteins of the two complexes are homologous. [6] However, cytochrome f and cytochrome c 1 are not homologous. [7]
In mammals, ten subunits are nuclear in origin, and three are synthesized in the mitochondria. The complex contains two hemes, a cytochrome a and cytochrome a 3, and two copper centers, the Cu A and Cu B centers. [3] In fact, the cytochrome a 3 and Cu B form a binuclear center that is the site of oxygen reduction.
Cytochrome is a heme-containing subunit of the cytochrome b-c1 complex, which accepts electrons from Rieske protein and transfers electrons to cytochrome c in the mitochondrial respiratory chain. [1] It is formed in the cytosol and targeted to the mitochondrial intermembrane space. Cytochrome c1 belongs to the cytochrome c family of proteins.
One electron is transferred to cytochrome c 1 from the 2Fe/2S centre, whilst another is transferred from the B L heme to the B H Heme. Cytochrome c 1 then transfers its electron to cytochrome c, whilst the nearby semiquinone produced from round 1 picks up a second electron from the B H heme, along with two protons from the matrix.
For example, the anthrax pathogen Bacillus anthracis releases two siderophores, bacillibactin and petrobactin, to scavenge ferric ion from iron containing proteins. While bacillibactin has been shown to bind to the immune system protein siderocalin , [ 12 ] petrobactin is assumed to evade the immune system and has been shown to be important for ...