|
Diazirine
Diazirines are a class of organic molecules consisting of a carbon bound to two nitrogen atoms, which are double-bonded to each other, forming a cyclopropene-like ring, 3''H''-diazirene. They are isomeric with diazocarbon groups, and like them can serve as precursors for carbenes by loss of a molecule of dinitrogen. For example, irradiation of diazirines with ultraviolet light leads to carbene insertion into various C-H, N-H, and O-H bonds. Hence, diazirines have grown in popularity as small photo-reactive crosslinking reagents. They are often used in photoaffinity labeling studies to observe a variety of interactions, including ligand-receptor, ligand-enzyme, protein-protein, and protein-nucleic acid interactions. Synthesis A number of methods exist in the literature for the preparation of diazirines, which begin from a variety of reagents. Synthesis from ketones Generally, synthetic schemes that begin with ketones involve conversion of the ketone with the desired substituen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbene
In organic chemistry, a carbene is a molecule containing a neutral carbon atom with a valence of two and two unshared valence electrons. The general formula is or where the R represents substituents or hydrogen atoms. The term "carbene" may also refer to the specific compound , also called methylene, the parent hydride from which all other carbene compounds are formally derived. Carbenes are classified as either singlets or triplets, depending upon their electronic structure. Most carbenes are very short lived, although persistent carbenes are known. One well-studied carbene is dichlorocarbene , which can be generated ''in situ'' from chloroform and a strong base. Structures and bonding The two classes of carbenes are singlet and triplet carbenes. Singlet carbenes are spin-paired. In the language of valence bond theory, the molecule adopts an sp2 hybrid structure. Triplet carbenes have two unpaired electrons. Most carbenes have a nonlinear triplet ground state, e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Graham Reaction
In organic chemistry, the Graham reaction is an oxidation reaction that converts an amidine into a diazirine using a hypohalite reagent. The halide of the hypohalite oxidant, or another similar anionic additive to the reaction, is retained as a substituent on the diazirine product. The reaction was first reported in 1965. Various reaction mechanisms have been proposed. : Amidine substrates for the reaction can easily be formed from the corresponding nitriles via the Pinner reaction. The halide substituent in the diazirine product can be displaced by a various nucleophile In chemistry, a nucleophile is a chemical species that forms bonds by donating an electron pair. All molecules and ions with a free pair of electrons or at least one pi bond can act as nucleophiles. Because nucleophiles donate electrons, they are ...s. : References {{Organic-chem-stub Ring forming reactions Organic oxidation reactions Amidines Diazirines ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diaziridine
Diaziridines are heterocyclic compounds containing two nitrogen atoms in a three-membered ring. They can be considered as strained hydrazines. Unlike most amine types of structures, the nitrogen atoms of diaziridines are configurationally stable because the ring strain prevents Walden inversion. As a result, there can be various stereoisomeric forms of this structure. They are usually synthesized by treating a carbonyl compound with an aminating reagent like hydroxylamine-''O''-sulfonic acid and either ammonia or a primary aliphatic amine under slightly basic conditions.Synthesis of monocyclic diaziridines and their fused derivatives; N. N. Makhova, V. Y. Petukhova, V. V. Kuznetsov, ''Arkivoc'', 2008(i), 128-15 The final step is based on the intramolecular cyclization of an aminal. Reactions * Unsubstituted diaziridines are often directly oxidized (I2/NEt3) to the more stable diazirines. * They can undergo ring expansion reaction with electrophilic reagents like ketenes or isoc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diazo
The diazo group is an organic moiety consisting of two linked nitrogen atoms ( azo) at the terminal position. Overall charge neutral organic compounds containing the diazo group bound to a carbon atom are called diazo compounds or diazoalkanes and are described by the general structural formula R2C=N+=N–. The simplest example of a diazo compound is diazomethane, CH2N2. Diazo compounds (R2C=N2) should not be confused with azo compounds of the type R-N=N-R or with diazonium compounds of the type R-N2+. Structure The electronic structure of diazo compounds is characterized by π electron density delocalized over the α-carbon and two nitrogen atoms, along with an orthogonal π system with electron density delocalized over only the terminal nitrogen atoms. Because all octet rule-satisfying resonance forms of diazo compounds have formal charges, they are members of a class of compounds known as 1,3-dipoles. Some of the most stable diazo compounds are α-diazo-β-diketones an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photoaffinity Labeling
Photoaffinity labeling is a chemoproteomics technique used to attach "labels" to the active site of a large molecule, especially a protein. The "label" attaches to the molecule loosely and reversibly, and has an inactive site which can be converted using photolysis into a highly reactive form, which causes the label to bind more permanently to the large molecule via a covalent bond. The technique was first described in the 1970s. Molecules that have been used as labels in this process are often analogs of complex molecules, in which certain functional groups are replaced with a photoreactive group, such as an azide, a diazirine or a benzophenone Benzophenone is the organic compound with the formula (C6H5)2CO, generally abbreviated Ph2CO. It is a white solid that is soluble in organic solvents. Benzophenone is a widely used building block in organic chemistry, being the parent diarylket .... References {{Reflist Molecular biology techniques ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Propofol
Propofol, marketed as Diprivan, among other names, is a short-acting medication that results in a decreased level of consciousness and a lack of memory for events. Its uses include the starting and maintenance of general anesthesia, sedation for mechanically ventilated adults, and procedural sedation. It is also used for status epilepticus if other medications have not worked. It is given by injection into a vein, and the maximum effect takes about two minutes to occur and typically lasts five to ten minutes. Propofol is also used for medical assistance in dying in Canada. The medication appears to be safe for use during pregnancy but has not been well studied for use in this case. It is not recommended for use during a cesarean section. It is not a pain medication, so opioids such as morphine may also be used; however, whether or not they are always needed is not clear. Propofol is believed to work at least partly via a receptor for GABA. Propofol was discovered in 1977 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GABAA Receptor
The GABAA receptor (GABAAR) is an ionotropic receptor and ligand-gated ion channel. Its endogenous ligand is γ-aminobutyric acid (GABA), the major inhibitory neurotransmitter in the central nervous system. Upon opening, the GABAA receptor on the postsynaptic cell is selectively permeable to chloride ions (Cl−) and, to a lesser extent, bicarbonate ions (HCO3−). Depending on the membrane potential and the ionic concentration difference, this can result in ionic fluxes across the pore. If the membrane potential is higher than the equilibrium potential (also known as the reversal potential) for chloride ions, when the receptor is activated Cl− will flow into the cell. This causes an inhibitory effect on neurotransmission by diminishing the chance of a successful action potential occurring at the postsynaptic cell. The reversal potential of the GABAA-mediated inhibitory postsynaptic potential (IPSP) in normal solution is −70 mV, contrasting the GABAB IPSP (-100 mV). T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anandamide
Anandamide (ANA), also known as ''N''-arachidonoylethanolamine (AEA), is a fatty acid neurotransmitter. Anandamide was the first endocannabinoid to be discovered: it participates in the body's endocannabinoid system by binding to cannabinoid receptors, the same receptors that the psychoactive compound THC in cannabis acts on. Anandamide is found in nearly all tissues in a wide range of animals. Anandamide has also been found in plants, including small amounts in chocolate. The name 'anandamide' is taken from the Sanskrit word '' ananda'', which means "joy, bliss, delight", plus amide. Anandamide is derived from the non-oxidative metabolism of arachidonic acid, an essential omega-6 fatty acid. It is synthesized from ''N''-arachidonoyl phosphatidylethanolamine by multiple pathways. It is degraded primarily by the fatty acid amide hydrolase (FAAH) enzyme, which converts anandamide into ethanolamine and arachidonic acid. As such, inhibitors of FAAH lead to elevated anandamide leve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypnotic
Hypnotic (from Greek ''Hypnos'', sleep), or soporific drugs, commonly known as sleeping pills, are a class of (and umbrella term for) psychoactive drugs whose primary function is to induce sleep (or surgical anesthesiaWhen used in anesthesia to produce and maintain unconsciousness, "sleep" is metaphorical as there are no regular sleep stages or cyclical natural states; patients rarely recover from anesthesia feeling refreshed and with renewed energy. The word is also used in art.) and to treat insomnia (sleeplessness). This group of drugs is related to sedatives''. ''Whereas the term sedative describes drugs that serve to calm or relieve anxiety, the term hypnotic generally describes drugs whose main purpose is to initiate, sustain, or lengthen sleep. Because these two functions frequently overlap, and because drugs in this class generally produce dose-dependent effects (ranging from anxiolysis to loss of consciousness), they are often referred to collectively as sedative-h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Etoposide
Etoposide, sold under the brand name Vepesid among others, is a chemotherapy medication used for the treatments of a number of types of cancer including testicular cancer, lung cancer, lymphoma, leukemia, neuroblastoma, and ovarian cancer. It is also used for hemophagocytic lymphohistiocytosis. It is used by mouth or intravenously, injection into a vein. Side effects are very common. They can include cytopenia, low blood cell counts, vomiting, loss of appetite, diarrhea, hair loss, and fever. Other severe side effects include allergic reactions and low blood pressure. Use during pregnancy will likely harm the fetus. Etoposide is in the topoisomerase inhibitor family of medication. It is believed to work by damaging DNA. Etoposide was approved for medical use in the United States in 1983. It is on the WHO Model List of Essential Medicines, World Health Organization's List of Essential Medicines. Medical uses Etoposide is used as a form of chemotherapy for cancers such as Kaposi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Type II Topoisomerase
Type II topoisomerases are topoisomerases that cut both strands of the DNA helix simultaneously in order to manage DNA tangles and supercoils. They use the hydrolysis of ATP, unlike Type I topoisomerase. In this process, these enzymes change the linking number of circular DNA by ±2. Topoisomerases are ubiquitous enzymes, found in all living organisms. In animals, topoisomerase II is a chemotherapy target. In prokaryotes, gyrase is an antibacterial target. Indeed, these enzymes are of interest for a wide range of effects. Function Type II topoisomerases increase or decrease the linking number of a DNA loop by 2 units, and it promotes chromosome disentanglement. For example, DNA gyrase, a type II topoisomerase observed in '' E. coli'' and most other prokaryotes, introduces negative supercoils and decreases the linking number by 2. Gyrase is also able to remove knots from the bacterial chromosome. Along with gyrase, most prokaryotes also contain a second type IIA topoisomerase, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
