|
Arsenite-Antimonite Efflux
Arsenite-antimonite transporters are membrane transporters that pump arsenite or antimonite out of a cell. Antimonite is the salt of antimony (Sb(III)) and has been found to significantly impact the toxicity of arsenite. The similar structure of As(III) and Sb(III) makes it plausible that certain transporters function in the efflux of both substrates. Arsenic efflux transporters exist in almost every organism and serve to remove this toxic compound from the cell. Subfamilies As of early 2016, there are at least three known families of proteins known to participate in arsenite and antimonite efflux. * ArsB familyTC# 2.A.45 * ArsAB FamilyTC# 3.A.4 * Arsenical resistance-3 (ARC3) familyTC#2.A.59 The membrane transporter ArsB can function as a secondary carrier or as a primary active transporter, in which case ArsA, an ATPase, must be superimposed onto ArsB. Arsenite and antimonite can also be pumped out of the cell by members of the ARC3 family, a member of the BART superfami ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Membrane Transporter
A membrane transport protein (or simply transporter) is a membrane protein involved in the movement of ions, small molecules, and macromolecules, such as another protein, across a biological membrane. Transport proteins are integral transmembrane proteins; that is they exist permanently within and span the membrane across which they transport substances. The proteins may assist in the movement of substances by facilitated diffusion or active transport. The two main types of proteins involved in such transport are broadly categorized as either ''channels'' or ''carriers''. The solute carriers and atypical SLCs are secondary active or facilitative transporters in humans. Collectively membrane transporters and channels are known as the transportome. Transportomes govern cellular influx and efflux of not only ions and nutrients but drugs as well. Difference between channels and carriers A carrier is not open simultaneously to both the extracellular and intracellular environments. Ei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arsenite
In chemistry, an arsenite is a chemical compound containing an arsenic oxyanion where arsenic has oxidation state +3. Note that in fields that commonly deal with groundwater chemistry, arsenite is used generically to identify soluble AsIII anions. IUPAC have recommended that arsenite compounds are to be named as arsenate(III), for example ortho-arsenite is called trioxidoarsenate(III). Ortho-arsenite contrasts to the corresponding anions of the lighter members of group 15, phosphite which has the structure and nitrite, which is bent. A number of different arsenite anions are known: * ortho-arsenite, an ion of arsenous acid, with a pyramidal shape * meta-arsenite, a polymeric chain anion. * pyro-arsenite, * a polyarsenite, * a polyarsenite, *, a polymeric anion In all of these the geometry around the AsIII centers are approximately trigonal, the lone pair on the arsenic atom is stereochemically active. Well known examples of arsenites include sodium meta-arsenite which contai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antimonite
In chemistry, antimonite refers to a salt of antimony(III), such as NaSb(OH)4 and NaSbO2 (meta-antimonite), which can be prepared by reacting alkali with antimony trioxide, Sb2O3.Egon Wiberg, Arnold Frederick Holleman (2001) ''Inorganic Chemistry'', Elsevier These are formally salts of antimonous acid, Sb(OH)3, whose existence in solution is dubious. Attempts to isolate it generally form Sb2O3·''x''H2O, antimony(III) oxide hydrate, which slowly transforms into Sb2O3. In geology, the mineral stibnite, Sb2S3, is sometimes called antimonite. Antimonites can be compared to antimonate In chemistry an antimonate is a compound which contains a metallic element, oxygen, and antimony in an oxidation state of +5. These compounds adopt polymeric structures with M-O-Sb linkages. They can be considered to be derivatives of the hypothetic ...s, which contain antimony in the +5 oxidation state. References Antimony(III) compounds Oxyanions {{inorganic-compound-stub th:สติบไ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ArsB And ArsAB Transporters
Arsenite resistance (Ars) efflux pumps of bacteria may consist of two proteins, ArsBTC# 2.A.45.1.1 the integral membrane constituent with twelve transmembrane spanners) and ArsATC# 3.A.4.1.1 the ATP-hydrolyzing, transport energizing subunit, as for the chromosomally-encoded ''E. coli'' system), or of one protein (just the ArsB integral membrane protein of the plasmid-encoded ''Staphylococcus'' system). ArsA proteins have two ATP binding domains and probably arose by a tandem gene duplication event. ArsB proteins all possess twelve transmembrane spanners and may also have arisen by a tandem gene duplication event. Structurally, the Ars pumps resemble ABC-type efflux pumps, but there is no significant sequence similarity between the Ars and ABC pumps. When only ArsB is present, the system operates by a pmf-dependent mechanism, and consequently belongs in TC subclass 2.A (i.eTC# 2.A.45. When ArsA is also present, ATP hydrolysis drives efflux, and consequently the system belongs in T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ARC3 Family
The arsenical resistance-3 (ACR3) familyTC# 2.A.59 is a member of the BART superfamily. Based on operon analyses, ARC3 homologues may function either as secondary carriers or as primary active transporters, similarly to the ArsB and ArsAB families. In the latter case ATP hydrolysis again energizes transport. ARC3 homologues transport the same anions as ArsA/AB homologues, though ArsB homologues are members of the IT Superfamily and homologues of the ARC3 family are within the BART Superfamily suggesting they may not be evolutionarily related. Structure and Homology ''Bacillus'' ARC3 (ArsBTC# 2.A.59.1.2 probably has a 10 TMS topology. ACR3 of ''S. cerevisiae'' is 404 amino acyl residues long and exhibits 10 putative transmembrane α-helical spanners (TMSs). Homologues are found in ''Mycobacterium tuberculosis'' (498 aas; gbZ80225), ''Archaeoglobus fulgidus'' (370 aas; gbAE001071), '' Methanobacterium thermoautotrophicum'' (365 aas; gbAE000865) and ''Synechocystis'' (383 aas; sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BART Superfamily
The Bile/Arsenite/Riboflavin Transporter (BART) superfamily is a superfamily SUPERFAMILY is a database and search platform of structural and functional annotation for all proteins and genomes. It classifies amino acid sequences into known structural domains, especially into SCOP superfamilies. Domains are functional, str ... of ubiquitous transport proteins. As of early 2016, the superfamily contains seven established families.Mansour, N.M., Sawhney, M., Tamang, D.G., Vogl, C., Saier, M.H. Jr. 2007. The bile-arsenite-riboflavin transporter (BART) superfamily FEBS Journal 274(3):612-29. Functional data for members of all of these families are available. The seven families are in the Transporter Classification Database with the following TC numbers, names and abbreviations include: *TC# 2.A.10- The 2-Keto-3-Deoxygluconate Transporter (KdgT) Family *TC# 2.A.28- The Bile Acid:Na+ Symporter (BASS) Family *TC# 2.A.59- The Arsenical Resistance-3 (ACR3) Family *TC# 2.A.69- The Auxin Ef ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ATP Hydrolysis
ATP hydrolysis is the catabolic reaction process by which chemical energy that has been stored in the high-energy phosphoanhydride bonds in adenosine triphosphate (ATP) is released after splitting these bonds, for example in muscles, by producing work in the form of mechanical energy. The product is adenosine diphosphate (ADP) and an inorganic phosphate (Pi). ADP can be further hydrolyzed to give energy, adenosine monophosphate (AMP), and another inorganic phosphate (Pi). ATP hydrolysis is the final link between the energy derived from food or sunlight and useful work such as muscle contraction, the establishment of electrochemical gradients across membranes, and biosynthetic processes necessary to maintain life. The description and typical textbook labels anhydridic bonds as "''high-energy bonds"''. P-O bonds are in fact fairly strong (~30 kJ/mol stronger than C-N bonds) Darwent, B. deB. (1970). "Bond Dissociation Energies in Simple Molecules", Nat. Stand. Ref. Data Ser., Na ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arsenic Toxicity
Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, but only the gray form, which has a metallic appearance, is important to industry. The primary use of arsenic is in alloys of lead (for example, in car batteries and ammunition). Arsenic is a common n-type dopant in semiconductor electronic devices. It is also a component of the III-V compound semiconductor gallium arsenide. Arsenic and its compounds, especially the trioxide, are used in the production of pesticides, treated wood products, herbicides, and insecticides. These applications are declining with the increasing recognition of the toxicity of arsenic and its compounds. A few species of bacteria are able to use arsenic compounds as respiratory metabolites. Trace quantities of arsenic are an essential dietary element in rats, hamsters, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arsenite-transporting ATPase
In enzymology, an arsenite-transporting ATPase () is an enzyme that catalyzes the chemical reaction :ATP + H2O + arsenitein \rightleftharpoons ADP + phosphate + arseniteout The 3 substrates of this enzyme are ATP, H2O, and arsenite, whereas its 3 products are ADP, phosphate In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid . The phosphate or orthophosphate ion is derived from phospho ..., and arsenite. This enzyme belongs to the family of hydrolases, specifically those acting on acid anhydrides acting on acid anhydrides to catalyse transmembrane movement of substances. The systematic name of this enzyme class is ATP phosphohydrolase (arsenite-exporting). Structural studies As of late 2007, 3 structures have been solved for this class of enzymes, with PDB accession codes , , and . See also * Arsenite-Antimonite efflux Reference ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Active Transport
In cellular biology, ''active transport'' is the movement of molecules or ions across a cell membrane from a region of lower concentration to a region of higher concentration—against the concentration gradient. Active transport requires cellular energy to achieve this movement. There are two types of active transport: primary active transport that uses adenosine triphosphate ( ATP), and secondary active transport that uses an electrochemical gradient. Some examples of active transport include: * Phagocytosis of bacteria by macrophages * Movement of calcium ions out of cardiac muscle cells * Transportation of amino acids across the intestinal lining in the human gut * Secretion of proteins such as enzymes, peptide hormones, and antibodies from various cells * Functioning of white blood cells to defend invading diseases Active cellular transportation (ACT) Unlike passive transport, which uses the kinetic energy and natural entropy of molecules moving down a gradient, active ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ATP-binding Cassette Transporter
The ATP-binding cassette transporters (ABC transporters) are a transport system superfamily that is one of the largest and possibly one of the oldest gene families. It is represented in all extant phyla, from prokaryotes to humans. ABC transporters belong to translocases. ABC transporters often consist of multiple subunits, one or two of which are transmembrane proteins and one or two of which are membrane-associated AAA ATPases. The ATPase subunits utilize the energy of adenosine triphosphate (ATP) binding and hydrolysis to provide the energy needed for the translocation of substrates across membranes, either for uptake or for export of the substrate. Most of the uptake systems also have an extracytoplasmic receptor, a solute binding protein. Some homologous ATPases function in non-transport-related processes such as translation of RNA and DNA repair. ABC transporters are considered to be an ABC superfamily based on the similarities of the sequence and organization of their ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
