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EGTA (chemical)
EGTA (ethylene glycol-bis(β-aminoethyl ether)-''N'',''N'',''N''′,''N''′-tetraacetic acid), also known as egtazic acid (INN, USAN), is an aminopolycarboxylic acid, a chelating agent. It is a white solid that is related to the better known EDTA. Compared to EDTA, it has a lower affinity for magnesium, making it more selective for calcium ions. It is useful in buffer solutions that resemble the environment in living cells where calcium ions are usually at least a thousandfold less concentrated than magnesium. The p''K''a for binding of calcium ions by tetrabasic EGTA is 11.00, but the protonated forms do not significantly contribute to binding, so at pH 7, the apparent p''K''a becomes 6.91. See Qin ''et al.'' for an example of a p''K''a calculation. EGTA has also been used experimentally for the treatment of animals with cerium poisoning and for the separation of thorium from the mineral monazite. EGTA is used as a compound in elution buffer in the protein purification te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Separation Process
A separation process is a method that converts a mixture or a solution (chemistry), solution of chemical substances into two or more distinct product mixtures, a scientific process of separating two or more substance in order to obtain purity. At least one product mixture from the separation is enriched in one or more of the source mixture's constituents. In some cases, a separation may fully divide the mixture into pure constituents. Separations exploit differences in chemical properties or physical properties (such as size, shape, mass, density, or chemical affinity) between the constituents of a mixture. Processes are often classified according to the particular properties they exploit to achieve separation. If no single difference can be used to accomplish the desired separation, multiple unit operation, operations can often be combined to achieve the desired end. With a few exceptions, chemical element, elements or Chemical compound, compounds exist in nature in an impure ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chelating Agents
Chelation is a type of bonding of ions and molecules to metal ions. It involves the formation or presence of two or more separate coordinate bonds between a polydentate (multiple bonded) ligand and a single central metal atom. These ligands are called chelants, chelators, chelating agents, or sequestering agents. They are usually organic compounds, but this is not a necessity, as in the case of zinc and its use as a maintenance therapy to prevent the absorption of copper in people with Wilson's disease. Chelation is useful in applications such as providing nutritional supplements, in chelation therapy to remove toxic metals from the body, as contrast agents in MRI scanning, in manufacturing using homogeneous catalysts, in chemical water treatment to assist in the removal of metals, and in fertilizers. Chelate effect The chelate effect is the greater affinity of chelating ligands for a metal ion than that of similar nonchelating (monodentate) ligands for the same metal. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BAPTA
BAPTA (1,2-bis(''o''- amino phenoxy)ethane-''N'',''N'',''N′'',''N′''-tetra acetic acid) is a calcium-specific aminopolycarboxylic acid. The presence of four carboxylic acid functional groups makes possible the binding of two calcium ions. The extensive flexibility of the carboxylate ligands is critical to the coordination of calcium and other metal ions. Due to its properties, it is used in research to chelate Ca2+, similarly to EGTA and EDTA. There is a range of reported values for the dissociation constant of BAPTA, though 0.2 μM appears consistently. The rate constant for calcium binding is 500 μM−1 s−1. See also * EDTA * EGTA * Fura-2 Fura-2, an aminopolycarboxylic acid, is a ratiometric fluorescent dye which binds to free intracellular calcium. It was the first widely used dye for calcium imaging, and remains very popular. Fura-2 is excited at 340 nm and 380 nm of ... References {{DEFAULTSORT:Bapta Anilines Carboxylic acids Chelating agents ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Smear Layer
In dentistry, the smear layer is a layer found on root canal walls after root canal instrumentation. It consists of microcrystalline and organic particle debris. It was first described in 1975 and research has been performed since then to evaluate its importance in bacteria penetration into the dentinal tubules and its effects on endodontic treatment. More broadly, it is the organic layer found over all hard tooth surfaces. Description Early studies of dentinal walls after cavity preparation performed by Brännström and Johnson (1974) showed the presence of a thin layer of debris that was 2 to 5 micrometres thick. In 1975 McComb and Smith first described the smear layer. They observed an amorphous layer of debris, with an irregular and granular surface, on instrumented dentinal walls using a scanning electron microscope (SEM). The thin, granular microcrystalline layer of debris was 2-5 micrometres thick and was found packed onto the canal wall. The authors stated that “most stan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endodontics
Endodontics (from the Greek roots ''endo-'' "inside" and ''odont-'' "tooth") is the dental specialty concerned with the study and treatment of the dental pulp. Overview Endodontics encompasses the study (practice) of the basic and clinical sciences of normal dental pulp, the etiology, diagnosis, prevention, and treatment of diseases and injuries of the dental pulp along with associated periradicular conditions. In clinical terms, endodontics involves either preserving part, or all of the dental pulp in health, or removing all of the pulp in irreversible disease. This includes teeth with irreversibly inflamed and infected pulpal tissue. Not only does endodontics involve treatment when a dental pulp is present, but also includes preserving teeth which have failed to respond to non-surgical endodontic treatment, or for teeth that have developed new lesions, e.g., when root canal re-treatment is required, or periradicular surgery. Endodontic treatment is one of the most comm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dentistry
Dentistry, also known as dental medicine and oral medicine, is the branch of medicine focused on the teeth, gums, and mouth. It consists of the study, diagnosis, prevention, management, and treatment of diseases, disorders, and conditions of the mouth, most commonly focused on dentition (the development and arrangement of teeth) as well as the oral mucosa. Dentistry may also encompass other aspects of the craniofacial complex including the temporomandibular joint. The practitioner is called a dentist. The history of dentistry is almost as ancient as the history of humanity and civilization with the earliest evidence dating from 7000 BC to 5500 BC. Dentistry is thought to have been the first specialization in medicine which have gone on to develop its own accredited degree with its own specializations. Dentistry is often also understood to subsume the now largely defunct medical specialty of stomatology (the study of the mouth and its disorders and diseases) for which reas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calmodulin
Calmodulin (CaM) (an abbreviation for calcium-modulated protein) is a multifunctional intermediate calcium-binding messenger protein expressed in all eukaryotic cells. It is an intracellular target of the secondary messenger Ca2+, and the binding of Ca2+ is required for the activation of calmodulin. Once bound to Ca2+, calmodulin acts as part of a calcium signal transduction pathway by modifying its interactions with various target proteins such as kinases or phosphatases. Structure Calmodulin is a small, highly conserved protein that is 148 amino acids long (16.7 kDa). The protein has two approximately symmetrical globular domains (the N- and C- domains) each containing a pair of EF hand motifs separated by a flexible linker region for a total of four Ca2+ binding sites, two in each globular domain. In the Ca2+-free state, the helices that form the four EF-hands are collapsed in a compact orientation, and the central linker is disordered; in the Ca2+-saturated state, th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Recombinant Fusion Protein
Fusion proteins or chimeric (kī-ˈmir-ik) proteins (literally, made of parts from different sources) are proteins created through the joining of two or more genes that originally coded for separate proteins. Translation of this ''fusion gene'' results in a single or multiple polypeptides with functional properties derived from each of the original proteins. ''Recombinant fusion proteins'' are created artificially by recombinant DNA technology for use in biological research or therapeutics. '' Chimeric'' or ''chimera'' usually designate hybrid proteins made of polypeptides having different functions or physico-chemical patterns. ''Chimeric mutant proteins'' occur naturally when a complex mutation, such as a chromosomal translocation, tandem duplication, or retrotransposition creates a novel coding sequence containing parts of the coding sequences from two different genes. Naturally occurring fusion proteins are commonly found in cancer cells, where they may function as oncoproteins ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tandem Affinity Purification
Tandem affinity purification (TAP) is an immunoprecipitation-based purification technique for studying protein–protein interactions. The goal is to extract from a cell only the protein of interest, in complex with any other proteins it interacted with. TAP uses two types of agarose beads that bind to the protein of interest and that can be separated from the cell lysate by centrifugation, without disturbing, denaturing or contaminating the involved complexes. To enable the protein of interest to bind to the beads, it is tagged with a designed piece, the TAP tag. The original TAP method involves the fusion of the TAP tag to the C-terminus of the protein under study. The TAP tag consists of three components: a calmodulin binding peptide (CBP), TEV protease cleavage site, and two Protein A domains, which bind tightly to IgG (making a TAP tag a type of epitope tag). Many other tag/bead/eluent combinations have been proposed since the TAP principle was first published. Variant ta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elution Volume
In analytical and organic chemistry, elution is the process of extracting one material from another by washing with a solvent; as in washing of loaded ion-exchange resins to remove captured ions. In a liquid chromatography experiment, for example, an analyte is generally adsorbed, or "bound to", an adsorbent in a liquid chromatography column. The adsorbent, a solid phase (stationary phase), is a powder which is coated onto a solid support. Based on an adsorbent's composition, it can have varying affinities to "hold" onto other molecules—forming a thin film on the surface of its particles. Elution then is the process of removing analytes from the adsorbent by running a solvent, called an "eluent", past the adsorbent/analyte complex. As the solvent molecules "elute", or travel down through the chromatography column, they can either pass by the adsorbent/analyte complex or they can displace the analyte by binding to the adsorbent in its place. After the solvent molecules displac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monazite
Monazite is a primarily reddish-brown phosphate mineral that contains rare-earth elements. Due to variability in composition, monazite is considered a group of minerals. The most common species of the group is monazite-(Ce), that is, the cerium-dominant member of the group. It occurs usually in small isolated crystals. It has a hardness of 5.0 to 5.5 on the Mohs scale of mineral hardness and is relatively dense, about 4.6 to 5.7 g/cm3. There are five different most common species of monazite, depending on the relative amounts of the rare earth elements in the mineral: * monazite-(Ce), ( Ce, La, Nd, Th) PO4 (the most common member), * monazite-(La), (La,Ce,Nd)PO4, * monazite-(Nd), (Nd,La,Ce)PO4, * monazite-(Sm), ( Sm, Gd,Ce,Th)PO4, * monazite-(Pr), ( Pr,Ce,Nd,Th)PO4. The elements in parentheses are listed in the order of their relative proportion within the mineral: lanthanum is the most common rare-earth element in monazite-(La), and so forth. Silica (SiO2) is present in trace a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
