Search results
Results From The WOW.Com Content Network
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.
In other words, the chemical compound would be designated with a capital letter, but specific instances in structures with lowercase. Thus cytochrome oxidase, which has two A hemes (heme a and heme a 3) in its structure, contains two moles of heme A per mole protein. Cytochrome bc 1, with hemes b H, b L, and c 1, contains heme B and heme C in a ...
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.
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.
The differences between those cytochromes lies in the different side-chains. For instance cytochrome a has a heme a prosthetic group and cytochrome b has a heme b prosthetic group. These differences result in different Fe 2+ /Fe 3+ redox potentials such that various cytochromes are involved in the mitochondrial electron transport chain. [17]
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.
The cytochrome b 6 f complex is a dimer, with each monomer composed of eight subunits. [3] These consist of four large subunits: a 32 kDa cytochrome f with a c-type cytochrome, a 25 kDa cytochrome b 6 with a low- and high-potential heme group, a 19 kDa Rieske iron-sulfur protein containing a [2Fe-2S] cluster, and a 17 kDa subunit IV; along with four small subunits (3-4 kDa): PetG, PetL, PetM ...