Chromatography, Thin Layer
Magnetic Resonance Spectroscopy
Characterisation of the conformational and quaternary structure-dependent heparin-binding region of bovine seminal plasma protein PDC-109. (1/78)PDC-109, the major heparin-binding protein of bull seminal plasma, binds to sperm choline lipids at ejaculation and modulates capacitation mediated by heparin. Affinity chromatography on heparin-Sepharose showed that polydisperse, but not monomeric, PDC-109 displayed heparin-binding capability. We sought to characterise the surface topology of the quaternary structure-dependent heparin-binding region of PDC-109 by comparing the arginine- and lysine-selective chemical modification patterns of the free and the heparin-bound protein. A combination of reversed-phase peptide mapping of endoproteinase Lys-C-digested PDC-109 derivatives and mass spectrometry was employed to identify modified and heparin-protected residues. PDC-109 contains two tandemly arranged fibronectin type II domains (a, Cys24-Cys61; b, Cys69-Cys109). The results show that six basic residues (Lys34, Arg57, Lys59, Arg64, Lys68, and Arg104) were shielded from reaction with acetic anhydride and 1,2-cyclohexanedione in heparin-bound PDC-109 oligomers. In the 1H-NMR solution structures of single fibronectin type II domains, residues topologically equivalent to PDC-109 Arg57 (Arg104) and Lys59 lay around beta-strand D on the same face of the domain. In full-length PDC-109, Arg64 and Lys68 are both located in the intervening polypeptide between domains a and b. Our data suggest possible quaternary structure arrangements of PDC-109 molecules to form a heparin-binding oligomer. (+info)
Chemical modification of lysine side chains of cyclodextrin glycosyltransferase from Thermoanaerobacter causes a shift from cyclodextrin glycosyltransferase to alpha-amylase specificity. (2/78)Cyclodextrin glycosyltransferases and alpha-amylases are two groups of enzymes with related secondary structures. However, cyclodextrin glycosyltransferases display transferase activities not present in alpha-amylases, probably derived from the existence of two more domains and different amino acid sequences. The hydrolytic activity of cyclodextrin glycosyltransferases is generally quite low, except for two cyclodextrin glycosyltransferases from termophiles. In this work, we have carried out the chemical modification (with acetic anhydride) of the amino groups of cyclodextrin glycosyltransferase from Thermoanaerobacter to assess their contributions to protein function. The acetylated cyclodextrin glycosyltransferase showed a significant reduction of its cyclization, coupling and disproportionation activities. Surprisingly, the hydrolytic (saccharifying) activity was slightly enhanced. These results suggest the participation of one or more lysine side chains in the interactions contributing to the transferase activity, either in any of the S11 subsites or in the acceptor binding site. (+info)
Induction and suppression of endothelial cell apoptosis by sphingolipids: a possible in vitro model for cell-cell interactions between platelets and endothelial cells. (3/78)Because sphingosine (Sph) is actively incorporated into platelets and rapidly converted to sphingosine 1-phosphate (Sph-1-P), which is then released extracellularly, it is important to study the effects of Sph and Sph-1-P on endothelial cells from the viewpoint of platelet-endothelial cell interaction. In this study, we found that Sph, as well as ceramide, induces apoptosis in human umbilical vein endothelial cells (HUVECs). In contrast, Sph-1-P acts as a HUVEC survival factor; this bioactive lipid was shown to protect HUVECs from apoptosis induced by the withdrawal of growth factors and to stimulate HUVEC DNA synthesis. In metabolic studies, [3H]Sph, incorporated into HUVECs, was converted to [3H]Cer and further to [3H]sphingomyelin in a time-dependent manner, whereas [3H]Sph-1-P formation from [3H]Sph was weak and transient. These findings in HUVECs are very different from those of platelets, which possess a highly active Sph kinase but lack Sph-1-P lyase. As a result, platelets abundantly store Sph-1-P, whereas HUVECs contain much less Sph-1-P. Finally, HUVECs, in contrast to platelets, failed to release Sph-1-P extracellularly, indicating that HUVECs themselves are not able to supply the survival factor Sph-1-P, but receive it from activated platelets. Our results suggest that platelets may maintain the integrity of endothelial cells by incorporating Sph and releasing Sph-1-P. (+info)
Distinguishing between luminal and localized proton buffering pools in thylakoid membranes. (4/78)The dual gradient energy coupling hypothesis posits that chloroplast thylakoid membranes are energized for ATP formation by either a delocalized or a localized proton gradient geometry. Localized energy coupling is characterized by sequestered domains with a buffering capacity of approximately 150 nmol H(+) mg(-1) chlorophyll (Chl). A total of 30 to 40 nmol mg(-1) Chl of the total sequestered domain buffering capacity is contributed by lysines with anomolously low pK(a)s, which can be covalently derivatized with acetic anhydride. We report that in thylakoid membranes treated with acetic anhydride, luminal acidification by a photosystem I (duraquinol [DQH(2)] to methyl viologen [MV]) proton pumping partial reaction was nearly completely inhibited, as measured by three separate assays, yet surprisingly, H(+) accumulation still occurred to the significant level of more than 100 nmol H(+) mg Chl(-1), presumably into the sequestered domains. The treatment did not increase the observed rate constant of dark H(+) efflux, nor was electron transport significantly inhibited. These data provide support for the existence of a sequestered proton translocating pathway linking the redox reaction H(+) ion sources with the CF(0) H(+) channel. The sequestered, low-pK(a) Lys groups appear to have a role in the H(+) diffusion process and chemically modifying them blocks the putative H(+) relay system. (+info)
Novel mechanism of surface catalysis of protein adduct formation. NMR studies of the acetylation of ubiquitin. (5/78)Reactivity of surface lysyl residues of proteins with a broad range of chemical agents has been proposed to be dependent on the catalytic microenvironment of the residue. We have investigated the acetylation of wild type ubiquitin and of the UbH68N mutant to evaluate the potential contribution of His-68 to the reactivity of Lys-6, which is about 4 A distant. These studies were performed using [1-(13)C]acetyl salicylate or [1,1'-(13)C(2)]acetic anhydride, and the acetylated products were detected by two-dimensional heteronuclear multiple quantum coherence spectroscopy. The results demonstrate that His-68 makes a positive contribution to the rate of acetylation of Lys-6 by labeled aspirin. Additionally, a pair of transient resonances is observed after treatment of wild type ubiquitin with the labeled acetic anhydride but not upon treatment of the H68N mutant. These resonances are assigned to the acetylated His-68 residue. The loss of intensity of the acetylhistidine resonances is accompanied by an increase in intensity of the acetyl-Lys-6 peak, supporting the existence of a transacetylation process between the acetylhistidine 68 and lysine 6 residues located on the protein surface. Hence, this may be the first direct demonstration of a catalytic intermediate forming on the protein surface. (+info)
Intramolecular capture of pummerer reaction intermediates by an aromatic nucleophile: selective construction of 1,4-benzothiazine and indole ring systems. (6/78)The simple alkyl sulfoxide 6 carrying two aromatic nucleophiles, when treated with trifluoroacetic anhydride at room temperature (Pummerer reaction conditions), underwent an intramolecular aromatic sulfenylation of the 6-exo-tet process in an exclusive manner to yield two regioisomeric 1,4-benzothiazine derivatives, 8 and 9. On the other hand, a similar reaction of the alpha-acyl sulfoxide 7, possessing identical aromatic nucleophiles, caused an intramolecular aromatic alkylation of the 5-exo-trig process to produce the 3-oxo-indole derivative 14 in a quantitative yield. These results demonstrate that the construction of 1,4-benzothiazine and indole ring systems can be achieved in a selective manner by proper choice of the sulfoxide side chain. (+info)
Trifluoromethyl ketone-based inhibitors of apoptosis in cerebellar granule neurons. (7/78)A variety of aromatic trifluoromethyl ketone derivatives has been studied as inhibitors of apoptosis in cerebellar granule neurons (CGNs). Among them, alpha-trifluoromethyl diketone (2) and benzyl trifluoromethyl ketone (11) were found to be apoptosis inhibitors which can prevent a neurodegenerative disease. Compounds 2 and 11 showed neuroprotection effect on low K+-induced apoptosis in CGNs. Furthermore, these compounds effectively suppressed DNA fragmentation accompanied with apoptosis. The neuroprotection mode of 2 and 11 was not related to inhibition of caspase-3. (+info)
Scandium(III) trifluoromethanesulfonate catalyzed aromatic nitration with inorganic nitrates and acetic anhydride. (8/78)The rare earth metal(III) trifluoromethanesulfonate (rare earth metal(III) triflate, RE(OTf)3) was found to be an efficient catalyst for aromatic nitration with carboxylic anhydride-inorganic nitrate as the nitrating agent. In the presence of a catalytic amount of RE(OTf)3, the nitration of substituted benzenes proceeded to afford the corresponding nitrobenzenes. Especially, scandium(III) trifluoromethanesulfonate (scandium(III) triflate, Sc(OTf)3) is the most active catalyst among our tested Lewis acids. It was also found that acetic anhydride-Al(NO3).9H2O is the most active nitrating agent in this system. (+info)
Acetic anhydride is a chemical compound with the formula CH3COOCO2H. It is a colorless, oily liquid with a strong, unpleasant smell. In the medical field, acetic anhydride is used as a reagent in the synthesis of various drugs and other chemical compounds. It is also used as a local anesthetic and as an antiseptic. However, it is important to note that acetic anhydride is highly toxic and can cause serious harm if not used properly. It is therefore important to use it only under the supervision of a qualified healthcare professional.
In the medical field, anhydrides refer to compounds that do not contain water molecules. Anhydrides can be found in various forms, including organic and inorganic compounds. One example of an anhydride in the medical field is acetylsalicylic acid, also known as aspirin. Aspirin is an organic anhydride that is commonly used as a pain reliever and anti-inflammatory medication. Another example of an anhydride in the medical field is sulfuric acid, which is an inorganic anhydride. Sulfuric acid is used in various medical applications, including as a preservative for vaccines and as a component in some medications. Overall, anhydrides play important roles in the medical field and are used in a variety of applications, from pain relief to vaccine preservation.
Succinic anhydride is a chemical compound that is used in the production of various pharmaceuticals and other chemicals. It is a white, crystalline solid that is soluble in organic solvents but not in water. In the medical field, succinic anhydride is used as a starting material for the synthesis of a number of drugs, including antibiotics, anticonvulsants, and analgesics. It is also used as a solvent and a chemical intermediate in the production of other chemicals.
Phthalic anhydrides are a class of organic compounds that are commonly used as intermediates in the production of various chemicals, including plastics, dyes, and pharmaceuticals. In the medical field, phthalic anhydrides are used as starting materials for the synthesis of a variety of drugs and other therapeutic agents. One example of a drug that is derived from phthalic anhydrides is diethyl phthalate (DEP), which is used as a solvent and plasticizer in medical devices and pharmaceuticals. DEP has been shown to have estrogenic effects in animal studies, which has raised concerns about its potential impact on human health. Other phthalic anhydrides that are used in the medical field include isophthalic anhydride, which is used as a starting material for the synthesis of certain antibiotics, and terephthalic anhydride, which is used in the production of resins and plastics that are used in medical devices. It is important to note that the use of phthalic anhydrides in the medical field is regulated by various government agencies, including the U.S. Food and Drug Administration (FDA), to ensure that they are safe and effective for their intended uses.
Maleic anhydride is a chemical compound that is not commonly used in the medical field. It is a white, crystalline solid that is used primarily as a chemical intermediate in the production of other chemicals, such as polymers and dyes. It is not used as a medication or for any medical purpose.
Neutral glycosphingolipids (NGSs) are a type of glycosphingolipid that do not contain charged groups on their sugar moieties. They are composed of a sphingosine backbone, a fatty acid chain, and a sugar moiety. NGSs are found in all mammalian cells and are important components of the cell membrane, playing roles in cell signaling, cell adhesion, and membrane trafficking. They are also involved in the pathogenesis of various diseases, including cancer, neurodegenerative disorders, and autoimmune diseases.
In the medical field, acetates refer to compounds that contain the acetate ion (CH3COO-). Acetates are commonly used in the treatment of various medical conditions, including: 1. Hyperkalemia: Acetate is used to treat high levels of potassium (hyperkalemia) in the blood. It works by binding to potassium ions and preventing them from entering cells, which helps to lower potassium levels in the blood. 2. Acidosis: Acetate is used to treat acidosis, a condition in which the blood becomes too acidic. It works by increasing the production of bicarbonate ions, which helps to neutralize excess acid in the blood. 3. Respiratory failure: Acetate is used to treat respiratory failure, a condition in which the lungs are unable to provide enough oxygen to the body. It works by providing an alternative source of energy for the body's cells, which helps to support the respiratory system. 4. Metabolic acidosis: Acetate is used to treat metabolic acidosis, a condition in which the body produces too much acid. It works by increasing the production of bicarbonate ions, which helps to neutralize excess acid in the body. 5. Hyperammonemia: Acetate is used to treat hyperammonemia, a condition in which the blood contains too much ammonia. It works by providing an alternative source of energy for the body's cells, which helps to reduce the production of ammonia. Overall, acetates are a useful tool in the treatment of various medical conditions, and their use is closely monitored by healthcare professionals to ensure their safe and effective use.
Citraconic anhydrides are a class of organic compounds that are used in various medical applications. They are typically derived from citric acid, which is a naturally occurring organic acid found in citrus fruits. One common use of citraconic anhydrides in medicine is as a preservative in pharmaceuticals and other medical products. They are also used as a stabilizer in certain types of medical devices, such as catheters and implants. Citraconic anhydrides are also used as a chelating agent, which means they can bind to certain metals and help to remove them from the body. This can be useful in the treatment of certain types of metal poisoning, such as lead poisoning. In addition to their medical uses, citraconic anhydrides are also used in a variety of other industries, including the food and beverage industry, where they are used as a flavor enhancer and preservative.
Lysine is an essential amino acid that is required for the growth and maintenance of tissues in the human body. It is one of the nine essential amino acids that cannot be synthesized by the body and must be obtained through the diet. Lysine plays a crucial role in the production of proteins, including enzymes, hormones, and antibodies. It is also involved in the absorption of calcium and the production of niacin, a B vitamin that is important for energy metabolism and the prevention of pellagra. In the medical field, lysine is used to treat and prevent various conditions, including: 1. Herpes simplex virus (HSV): Lysine supplements have been shown to reduce the frequency and severity of outbreaks of HSV-1 and HSV-2, which cause cold sores and genital herpes, respectively. 2. Cold sores: Lysine supplements can help reduce the frequency and severity of cold sore outbreaks by inhibiting the replication of the herpes simplex virus. 3. Depression: Lysine has been shown to increase levels of serotonin, a neurotransmitter that regulates mood, in the brain. 4. Hair loss: Lysine is important for the production of hair, and deficiency in lysine has been linked to hair loss. 5. Wound healing: Lysine is involved in the production of collagen, a protein that is important for wound healing. Overall, lysine is an important nutrient that plays a crucial role in many aspects of human health and is used in the treatment and prevention of various medical conditions.
Tritium is a radioactive isotope of hydrogen with the atomic number 3 and the symbol T. It is a beta emitter with a half-life of approximately 12.3 years. In the medical field, tritium is used in a variety of applications, including: 1. Medical imaging: Tritium is used in nuclear medicine to label molecules and track their movement within the body. For example, tritium can be used to label antibodies, which can then be injected into the body to track the movement of specific cells or tissues. 2. Radiation therapy: Tritium is used in radiation therapy to treat certain types of cancer. It is typically combined with other isotopes, such as carbon-14 or phosphorus-32, to create a radioactive tracer that can be injected into the body and targeted to specific areas of cancerous tissue. 3. Research: Tritium is also used in research to study the behavior of molecules and cells. For example, tritium can be used to label DNA, which can then be used to study the process of DNA replication and repair. It is important to note that tritium is a highly radioactive isotope and requires careful handling to minimize the risk of exposure to radiation.
Acetic oxalic anhydride
Acetic formic anhydride
Organic acid anhydride
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Acetic anhydride ACS reagent, = 98.0 108-24-7
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- 2-Butoxyethanol is acid, acetic acid anhydride, or acetic acid chloride. (cdc.gov)
Extracted with dichloromethane1
- Urine samples collected from 15 exposed workers (N = 111) were subjected to acid hydrolysis and extracted with dichloromethane, then derivatized with acetic anhydride. (nih.gov)
- [ 48 , 49 ] Acetic anhydride derivatization is best utilized if a deuterated version is used, as shown previously to quantify the acetylation isomers on histone H4 and developmental changes of core histones from Drosophila melanogaster . (medscape.com)
- The chips were reacted with acetic, succinic, maleic and phthalic anhydride at constant temperature for 3 hours then, hot pressed at 150 °C by using phenol for. (irg-wp.com)
- Ethanol ignites and then explodes on contact with acetic anhydride + sodium hydrosulfate (ignites and may explode), disulfuric acid + nitric acid, phosphorous(III) oxide platinum, potassium-tert-butoxide+ acids. (libertynatural.com)
- Genetic Toxicity Evaluation of Acetic Anhydride in Salmonella/E.coli Mutagenicity Test or Ames Test. (nih.gov)
- The extracts were derivatized with acetic anhydride and excess reagent was removed with phosphate buffer and sodium sulfate before sample was dried and reconstituted with water for analysis. (cdc.gov)
- Prior to proteolysis, the highly charged histones may be chemically derivatized using acetic or propionic anhydride. (medscape.com)
- Intriguingly, methods have been refined to include the use of isotopically labeled propionic anhydride to compare PTM abundances between multiple sample types. (medscape.com)
- Another series of 2,3-disubstituted-4(3 H )-quinazolinones has been also obtained from reactions of a 3-aminoquinazolin-4(3 H )-one derivative with other carbon electrophiles, such as chloroacetamide, acetic anhydride, phenyl isocyanate, and ethyl chloroacetate. (heterocycles.jp)
- Industry uses carbon monoxide to manufacture compounds such as acetic anhydride, polycarbonates, acetic acid and polyketone. (cdc.gov)
- It is it may also be made by the reaction of ethylene prepared by reacting 2-butoxyethanol with acetic glycol with dibutyl sulfate. (cdc.gov)
- Reacts with water to form acetic acid. (cdc.gov)