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Hydroxybenzotriazole
Hydroxybenzotriazole (abbreviated HOBt) is an organic compound with the formula . It is a derivative of benzotriazole. It is a white crystalline powder, which as a commercial product contains some water (~11.7% wt as the HOBt monohydrate crystal). Anhydrous HOBt is explosive. It is mainly used to suppress the racemization and to improve the efficiency of peptide synthesis. Use in peptide synthesis Automated peptide synthesis involves the condensation of the amino group of protected amino acids with the activated ester. HOBt is used to produce such activated esters which react with amines at ambient temperature to give amides. HOBt is also used for the synthesis of amides from carboxylic acids aside from amino acids. These substrates may not be convertible to the acyl chlorides. Safety Due to reclassification as UN0508, a class 1.3C explosive, hydroxybenzotriazole and its monohydrate crystal are no longer allowed to be transported by sea or air as per 49CFR (USDOT hazard ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Activated Ester
In organic chemistry, an active ester is an ester functional group that is highly susceptible toward nucleophilic attack. Activation can be imparted by modifications of the acyl or the alkoxy components of a normal ester, say ethyl acetate. Typical modifications call for electronegative substituents. Active esters are employed in both synthetic and biological chemistry. Reactivity Active esters are mainly used as acylation, acylating agents. They undergo the same reactions as their unactivated analogues but do so more rapidly. They are prone to hydrolysis, for example. Of great interest is the enhanced reactivity of active esters toward amines to give amides. Examples Biochemistry image:3'-Phosphoadenosine-5'-phosphosulfate.svg, 120px, 3'-Phosphoadenosine-5'-phosphosulfate is an active ester of sulfate. Active esters are prominent in biochemistry. Glutamine synthetase is an enzyme that forms an active ester from the terminal carboxylate of glutamic acid. This activation, impar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of UN Numbers 0501 To 0600
UN numbers from UN0501 to UN0600 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods are as follows: __NOTOC__ UN 0501 to UN 0600 See also *Lists of UN numbers The UN numbers range from UN0001 to about UN3600 and are assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods. UN 0001 to 0600 * List of UN numbers 0001 to 0100 * List of UN numbers 0101 to 0200 * List of UN n ... External linksADR Dangerous Goods cited on 4 June 2015.UN Dangerous Goods List from 2015 cited on 4 June 2015.UN Dangerous Goods List from 2013 cited on 4 June 2015. {{UN number list navbox Lists of UN numbers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Compound
Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-containing compounds such as alkanes (e.g. methane ) and its derivatives are universally considered organic, but many others are sometimes considered inorganic, such as certain compounds of carbon with nitrogen and oxygen (e.g. cyanide ion , hydrogen cyanide , chloroformic acid , carbon dioxide , and carbonate ion ). Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The study of the properties, reactions, and syntheses of organic compounds comprise the discipline known as organic chemistry. For historical reasons, a few classes of carbon-containing compounds (e.g., carbonate salts and cyanide salts), along with a few other exceptions (e.g., carbon dioxide, and even ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of UN Numbers 3401 To 3500
A list is a set of discrete items of information collected and set forth in some format for utility, entertainment, or other purposes. A list may be memorialized in any number of ways, including existing only in the mind of the list-maker, but lists are frequently written down on paper, or maintained electronically. Lists are "most frequently a tool", and "one does not ''read'' but only ''uses'' a list: one looks up the relevant information in it, but usually does not need to deal with it as a whole".Lucie Doležalová,The Potential and Limitations of Studying Lists, in Lucie Doležalová, ed., ''The Charm of a List: From the Sumerians to Computerised Data Processing'' (2009). Purpose It has been observed that, with a few exceptions, "the scholarship on lists remains fragmented". David Wallechinsky, a co-author of ''The Book of Lists'', described the attraction of lists as being "because we live in an era of overstimulation, especially in terms of information, and lists help us ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reagents For Biochemistry
In chemistry, a reagent ( ) or analytical reagent is a substance or compound added to a system to cause a chemical reaction, or test if one occurs. The terms ''reactant'' and ''reagent'' are often used interchangeably, but reactant specifies a substance ''consumed'' in the course of a chemical reaction. ''Solvents'', though involved in the reaction mechanism, are usually not called reactants. Similarly, ''catalysis, catalysts'' are not consumed by the reaction, so they are not reactants. In biochemistry, especially in connection with enzyme-catalyzed reactions, the reactants are commonly called substrate (biochemistry), substrates. Definitions Organic chemistry In organic chemistry, the term "reagent" denotes a chemical ingredient (a compound or mixture, typically of inorganic or small organic molecules) introduced to cause the desired transformation of an organic substance. Examples include the Collins reagent, Fenton's reagent, and Grignard reagents. Analytical chemistry ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biochemistry
Biochemistry, or biological chemistry, is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology, and metabolism. Over the last decades of the 20th century, biochemistry has become successful at explaining living processes through these three disciplines. Almost all List of life sciences, areas of the life sciences are being uncovered and developed through biochemical methodology and research.#Voet, Voet (2005), p. 3. Biochemistry focuses on understanding the chemical basis that allows biomolecule, biological molecules to give rise to the processes that occur within living Cell (biology), cells and between cells,#Karp, Karp (2009), p. 2. in turn relating greatly to the understanding of tissue (biology), tissues and organ (anatomy), organs as well as organism structure and function.#Miller, Miller (2012). p. 62. Biochemistry is closely ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peptide Coupling Reagents
Peptides are short chains of amino acids linked by peptide bonds. A polypeptide is a longer, continuous, unbranched peptide chain. Polypeptides that have a molecular mass of 10,000 Da or more are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides. Peptides fall under the broad chemical classes of biological polymers and oligomers, alongside nucleic acids, oligosaccharides, polysaccharides, and others. Proteins consist of one or more polypeptides arranged in a biologically functional way, often bound to ligands such as coenzymes and cofactors, to another protein or other macromolecule such as DNA or RNA, or to complex macromolecular assemblies. Amino acids that have been incorporated into peptides are termed residues. A water molecule is released during formation of each amide bond.. All peptides except cyclic peptides have an N-terminal (amine group) and C-terminal (carboxyl group) residu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
OECD
The Organisation for Economic Co-operation and Development (OECD; , OCDE) is an international organization, intergovernmental organization with 38 member countries, founded in 1961 to stimulate economic progress and international trade, world trade. It is a forum (legal), forum whose member countries describe themselves as committed to democracy and the market economy, providing a platform to compare policy experiences, seek answers to common problems, identify good practices, and coordinate domestic and international policies of its members. The majority of OECD members are generally regarded as developed country, developed countries, with High-income economy, high-income economies, and a very high Human Development Index. their collective population is 1.38 billion people with an average life expectancy of 80 years and a median age of 40, against a global average of 30. , OECD Member countries collectively comprised 62.2% of list of countries by GDP (nominal), global nom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Local Lymph Node Assay
The murine local lymph node assay (LLNA) is an ''in vivo'' test for skin sensitisation. LLNA has largely superseded the guinea pig maximisation test and the Buehler test. It is considered more scientific and less cruel (lower number of animals; less suffering) and has found broad scientific and regulatory acceptance. The principle underlying the LLNA is that skin sensitizers induce growth of lymphocytes in the lymph nodes draining the site of application. Lymphocyte proliferation can be measured by radiolabeling (quantifying tritiaded thymidine), bioluminescence (quantifying ATP content in lymphocytes) or immunoassay (ELISA utilizing an antibody specific for BrdU). The test material is applied to the ears of mice. Optionally, a tracer substance such as 3H-Methyl-thymidine or BrdU is injected intraperitoneally for lymphocyte incorporation. The animals are euthanized and their lymph node cells are removed and analyzed. The ratio of tracer incorporation in lymph nodes from dos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sensitization (immunology)
In immunology, the term sensitization is used for the following concepts:Anderson DM, ed. (2003). "Sensitization." ''Dorland's Illustrated Medical Dictionary'', 30th ed. Philadelphia: Saunders, p. 1680. .Brown MJ, ed. (1992). "Sensitization." ''Miller-Keane Encyclopedia & Dictionary of Medicine, Nursing, and Allied Health'', 5th ed. Philadelphia; London: Saunders, p. 1352. .Pugh MB, ed. (2000). "Sensitization." ''Stedman's Medical Dictionary'', 27th ed. Philadelphia: Lippincott Williams and Wilkins, p. 1619. .Tada T, Taniguchi M, Okumura Y, Miyasaka M, eds. (1993). "Sensitization." ''Dictionary of Terms in Immunology'', 3rd ed. Osaka: Saishin-Igakusha, Ltd., p. 510. C3547 (in Japanese). * Immunization by inducing an adaptive response in the immune system. In this sense, sensitization is the term more often in usage for induction of allergic responses.Janeway C, Travers P, Walport M, Shlomchik M, eds. (2001). ''Immunobiology 5: The Immune System in Health and Disease.'' New York: Ga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
