Proton Pump
A proton pump is an integral membrane protein pump that builds up a proton gradient across a biological membrane. Proton pumps catalyze the following reaction: : n one side of a biological membrane/sub> + energy n the other side of the membrane/sub> Mechanisms are based on energy-induced conformational changes of the protein structure or on the Q cycle. During evolution, proton pumps have arisen independently on multiple occasions. Thus, not only throughout nature, but also within single cells, different proton pumps that are evolutionarily unrelated can be found. Proton pumps are divided into different major classes of pumps that use different sources of energy, exhibiting different polypeptide compositions and evolutionary origins. Function Transport of the positively charged proton is typically electrogenic, i.e.: it generates an electric field across the membrane also called the membrane potential. Proton transport becomes electrogenic if not neutralized electrica ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Proton Beam
A charged particle beam is a spatially localized group of electrically charged particles that have approximately the same position, kinetic energy (resulting in the same velocity), and direction. The kinetic energies of the particles are much larger than the energies of particles at ambient temperature. The high energy and directionality of charged particle beams make them useful for many applications in particle physics (see Particle beam#Applications and Electron-beam technology). Such beams can be split into two main classes: # ''unbunched beams'' (''coasting beams'' or ''DC beams''), which have no longitudinal substructure in the direction of beam motion. # ''bunched beams'', in which the particles are distributed into pulses (bunches) of particles. Bunched beams are most common in modern facilities, since the most modern particle accelerators require bunched beams for acceleration. Assuming a normal distribution of particle positions and impulses, a charged particle b ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Buffering Agent
A buffer solution is a solution where the pH does not change significantly on dilution or if an acid or base is added at constant temperature. Its pH changes very little when a small amount of strong acid or base is added to it. Buffer solutions are used as a means of keeping pH at a nearly constant value in a wide variety of chemical applications. In nature, there are many living systems that use buffering for pH regulation. For example, the bicarbonate buffering system is used to regulate the pH of blood, and bicarbonate also acts as a buffer in the ocean. Principles of buffering Buffer solutions resist pH change because of a chemical equilibrium between the weak acid HA and its conjugate base A−: When some strong acid is added to an equilibrium mixture of the weak acid and its conjugate base, hydrogen ions (H+) are added, and the equilibrium is shifted to the left, in accordance with Le Chatelier's principle. Because of this, the hydrogen ion concentration increas ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Catalyze
Catalysis () is the increase in rate of a chemical reaction due to an added substance known as a catalyst (). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quickly, very small amounts of catalyst often suffice; mixing, surface area, and temperature are important factors in reaction rate. Catalysts generally react with one or more reactants to form intermediates that subsequently give the final reaction product, in the process of regenerating the catalyst. The rate increase occurs because the catalyst allows the reaction to occur by an alternative mechanism which may be much faster than the noncatalyzed mechanism. However the noncatalyzed mechanism does remain possible, so that the total rate (catalyzed plus noncatalyzed) can only increase in the presence of the catalyst and never decrease. Catalysis may be classified as either homogeneous, whose components are dispersed in the same phase (usual ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Mrp Superfamily
The Na+ Transporting Mrp Superfamily is a superfamily of integral membrane transport proteins. It includes the TC families:2.A.63- The Monovalent Cation (K+ or Na+):Proton Antiporter-3 (CPA3) Family3.D.1- The H+ or Na+-translocating NADH Dehyrogenase (NDH) Family3.D.9- The H+-translocating F420H2 Dehydrogenase (F420H2DH) Family Mrp of ''Bacillus subtilis'' is a 7 subunit Na+/H+ antiporter An antiporter (also called exchanger or counter-transporter) is an integral membrane protein that uses secondary active transport to move two or more molecules in opposite directions across a phospholipid membrane. It is a type of cotransporte ... comple(TC# 2.A.63.1.4) All subunits are homologous to the subunits in other members of this monovalent cation (K+ or Na+):proton antiporter-3 (CPA3) family as well as subunits in the archaeal hydrogenasesTC#s 3.D.1.4.1an3.D.1.4.2, which share several subunits with NADH dehydrogenase subunits (3.D.1). The largest subunits of the Mrp complex (Mrp ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Respiratory Complex I
Respiratory complex I, (also known as NADH:ubiquinone oxidoreductase, Type I NADH dehydrogenase and mitochondrial complex I) is the first large protein complex of the Electron transport chain, respiratory chains of many organisms from bacteria to humans. It catalyzes the transfer of electrons from NADH to coenzyme Q10 (CoQ10) and translocates protons across the inner mitochondrial membrane in eukaryotes or the plasma membrane of bacteria. This enzyme is essential for the normal functioning of cells, and mutations in its subunits lead to a wide range of inherited neuromuscular and metabolic disorders. Defects in this enzyme are responsible for the development of several pathological processes such as Reperfusion injury, ischemia/reperfusion damage (stroke and Myocardial infarction, cardiac infarction), Parkinson's disease and others. Function Complex I is the first enzyme of the Electron transport chain#Mitochondrial electron transport chains, mitochondrial electron tr ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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NADH Dehydrogenase
NADH dehydrogenase is an enzyme that converts nicotinamide adenine dinucleotide (NAD) from its reduced form (NADH) to its oxidized form (NAD+). Members of the NADH dehydrogenase family and analogues are commonly systematically named using the format ''NADH:acceptor oxidoreductase''. The chemical reaction these enzymes catalyze is generally represented with the following equation: : NADH + H+ + acceptor NAD+ + reduced acceptor NADH dehydrogenase is a flavoprotein that contains iron-sulfur centers. NADH dehydrogenase is used in the electron transport chain for generation of ATP. The EC term NADH dehydrogenase (quinone) (EC 1.6.5.11) is defined for NADH dehydrogenases that use a quinone The quinones are a class of organic compounds that are formally "derived from aromatic compounds benzene.html" ;"title="uch as benzene">uch as benzene or naphthalene] by conversion of an even number of –CH= groups into –C(=O)– groups with ... (excluding ubiquinone) as the acceptor. ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Proton ATPase
In the field of enzymology, a proton ATPase, or H+-ATPase, is an enzyme that catalyzes the following chemical reaction: :ATP + + in \rightleftharpoons ADP + phosphate + out The 3 substrates of this enzyme are ATP, , and , whereas its 3 products are ADP, phosphate, and . Proton ATPases are divided into three groups as outlined below: P-type proton ATPase P-type ATPases form a covalent phosphorylated (hence the symbol ’P') intermediate as part of its reaction cycle. P-type ATPases undergo major conformational changes during the catalytic cycle. P-type ATPases are not evolutionary related to V- and F-type ATPases. Plasma membrane H+-ATPase P-type proton ATPase (or plasma membrane -ATPase) is found in the plasma membranes of eubacteria, archaea, protozoa, fungi and plants. Here it serves as a functional equivalent to the Na+/K+ ATPase of animal cells; i.e. it energizes the plasma membrane by forming an electrochemical gradient of protons (Na+ in animal cells), that in t ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Adenosine Triphosphate
Adenosine triphosphate (ATP) is a nucleoside triphosphate that provides energy to drive and support many processes in living cell (biology), cells, such as muscle contraction, nerve impulse propagation, and chemical synthesis. Found in all known forms of life, it is often referred to as the "molecular unit of currency" for intracellular energy transfer. When consumed in a Metabolism, metabolic process, ATP converts either to adenosine diphosphate (ADP) or to adenosine monophosphate (AMP). Other processes regenerate ATP. It is also a Precursor (chemistry), precursor to DNA and RNA, and is used as a coenzyme. An average adult human processes around 50 kilograms (about 100 mole (unit), moles) daily. From the perspective of biochemistry, ATP is classified as a nucleoside triphosphate, which indicates that it consists of three components: a nitrogenous base (adenine), the sugar ribose, and the Polyphosphate, triphosphate. Structure ATP consists of three parts: a sugar, an amine base ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Proton-pumping Pyrophosphatase
Members of the H+, Na+-translocating Pyrophosphatase (M+''-PPase)'' FamilyTC# 3.A.10 are found in the vacuolar (tonoplast) membranes of higher plants, algae, and protozoa, and in both bacteria and archaea. They are therefore ancient enzymes. Two types of inorganic diphosphatase, very different in terms of both amino acid sequence and structure, have been characterised to date: soluble and transmembrane proton-pumping pyrophosphatases (sPPases and H(+)-PPases, respectively). sPPases are ubiquitous proteins that hydrolyse pyrophosphate to release heat, whereas H+-PPases, so far unidentified in animal and fungal cells, couple the energy of PPi hydrolysis to proton movement across biological membranes. The latter type is represented by this group of proteins. H+-PPases vacuolar-type inorganic pyrophosphatases (V-PPase) or pyrophosphate-energised vacuolar membrane proton pumps. In plants, vacuoles contain two enzymes for acidifying the interior of the vacuole, the V-ATPase and the V- ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Pyrophosphate
In chemistry, pyrophosphates are phosphorus oxyanions that contain two phosphorus atoms in a linkage. A number of pyrophosphate salts exist, such as disodium pyrophosphate () and tetrasodium pyrophosphate (), among others. Often pyrophosphates are called diphosphates. The parent pyrophosphates are derived from partial or complete neutralization of pyrophosphoric acid. The pyrophosphate bond is also sometimes referred to as a phosphoanhydride bond, a naming convention which emphasizes the loss of water that occurs when two phosphates form a new bond, and which mirrors the nomenclature for Organic acid anhydride, anhydrides of carboxylic acids. Pyrophosphates are found in Adenosine triphosphate, ATP and other nucleotide triphosphates, which are important in biochemistry. The term pyrophosphate is also the name of esters formed by the condensation of a phosphorylated biological compound with inorganic phosphate, as for dimethylallyl pyrophosphate. This bond is also referred to as a ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Cytochrome C Oxidase
The enzyme cytochrome c oxidase or Complex IV (was , now reclassified as a translocasEC 7.1.1.9 is a large transmembrane protein complex found in bacteria, archaea, and the mitochondria of eukaryotes. It is the last enzyme in the Cellular respiration, respiratory electron transport chain of cell (biology), cells located in the membrane. It receives an electron from each of four cytochrome c molecules and transfers them to one oxygen molecule and four protons, producing two molecules of water. In addition to binding the four protons from the inner aqueous phase, it transports another four protons across the membrane, increasing the transmembrane difference of proton electrochemical potential, which the ATP synthase then uses to synthesize Adenosine triphosphate, ATP. Structure The complex The complex is a large integral membrane protein composed of several Cofactor (biochemistry)#Metal ions, metal prosthetic sites and 13 protein subunits in mammals. In mammals, ten subunits a ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Coenzyme Q – Cytochrome C Reductase
The coenzyme Q : cytochrome ''c'' – oxidoreductase, sometimes called the cytochrome ''bc''1 complex, and at other times complex III, is the third complex in the electron transport chain (), playing a critical role in biochemical generation of ATP (oxidative phosphorylation). Complex III is a multisubunit transmembrane protein encoded by both the mitochondrial (cytochrome b) and the nuclear genomes (all other subunits). Complex III is present in the mitochondria of all animals and all aerobic eukaryotes and the inner membranes of most bacteria. Mutations in Complex III cause exercise intolerance as well as multisystem disorders. The bc1 complex contains 11 subunits, 3 respiratory subunits (cytochrome B, cytochrome C1, Rieske protein), 2 core proteins and 6 low-molecular weight proteins. Ubiquinol—cytochrome-c reductase catalyzes the chemical reaction :QH2 + 2 ferricytochrome c \rightleftharpoons Q + 2 ferrocytochrome c + 2 H+ Thus, the two substrates of this enzyme are qui ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |