Molecular compounds

Xem 1-20 trên 67 kết quả Molecular compounds
  • Escherichia coliphosphotransacetylase (Pta) catalyzes the reversible inter-conversion of acetyl-CoA and acetyl phosphate. Both compounds are critical in E. colimetabolism, and acetyl phosphate is also involved in the regulation of certain signal transduction pathways. Along with acetate kinase, Pta plays an important role in acetate production when E.

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  • Phthiocerol and phthiodiolone dimycocerosates (DIMs) and phenolic gly-colipids (PGLs) are complex lipids located at the cell surface ofMycobacte-rium tuberculosis that play a key role in the pathogenicity of tuberculosis. Most of the genes involved in the biosynthesis of these compounds are clustered on a region of the M. tuberculosischromosome, the so-called DIM + PGL locus.

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  • Chemical substances (also called pure substances) may well be defined as "any material with a definite chemical composition" in an introductory general chemistry textbook.[2] According to this definition a chemical substance can either be a pure chemical element or a pure chemical compound. But, there are exceptions to this definition; a pure substance can also be defined as a form of matter that has both definite composition and distinct properties.[3] The chemical substance index published by CAS also includes several alloys of uncertain composition.

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  • After the ground breaking discovery of electrical charge carrier transport in polymers in the late 1980s by Alan J. Heeger, Alan G. MacDiarmid and Hideki Shirakawa [1–3], who were awarded the Nobel Prize in chemistry in 2000, the question arose as to whether organic materials would also find applications as organic semiconductors. This field really started to attract major attention after the demonstration of the first organic light emitting device (OLED) in 1987 by Tang and Van Slyke [4].

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  • In gravity injection, small volumes of reagents are gravity-fed into injection well(s) over a longer application period. The distribution and dissipation of the reagents in the saturated zone is largely controlled by the site hydrogeologic conditions. The gravity injection approach may reduce some of risks associated with chemical oxidation technologies. Additionally, given its prolonged application period, the oxidants may be able to penetrate into more of the lower permeability soils to address contaminants in these areas.

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  • Plants defend themselves from other organisms by elaborating bioactive chemical defences. This is the essential basis of the use of herbal medicines that still represents a major therapeutic resort for much of humanity However, at the outset, it must be stated that any plant that is not part of our evolved dietary cultures is potentially dangerous. Commercial herbal medicinal preparations approved by expert regulatory authorities have a significant place in mainstream conventional medicine and in complementary medicine.

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  • Chemists frequently refer to chemical compounds using chemical formulae or molecular structure of the compound. There has been a phenomenal growth in the number of chemical compounds being synthesized (or isolated), and then reported in the scientific literature by professional chemists around the world.[13] An enormous number of chemical compounds are possible through the chemical combination of the known chemical elements. As of May 2011, about sixty million chemical compounds are known.

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  • The protein arginine methyltransferase (PRMT) family of enzymes cata-lyzes the transfer of methyl groups from S-adenosylmethionine to the gua-nidino nitrogen atom of peptidylarginine to form monomethylarginine or dimethylarginine. We created several less polar analogs of the specific PRMT inhibitor arginine methylation inhibitor-1, and one such compound was found to have improved PRMT inhibitory activity over the parent molecule.

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  • There is a growing body of evidence which demonstrates that following a diet that complies with the Dietary Guidelines may reduce the risk of chronic disease. Recently, it was reported that dietary patterns consistent with recommended dietary guidance were associated with a lower risk of mortality among individuals age 45 years and older in the United States.

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  • Consequently the chemical contamination builds to higher levels in these organisms. Indigenous peoples in the Arctic, whose traditional diets are heavy in fatty foods and who often have no alternatives for nourishment, thus have some of the highest recorded levels of POPs. Yet they are hundreds or thousands of kilometres from where these pesticides and industrial chemicals were released, and they certainly received little benefit from the chemicals' original use.

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  • Freshwater sponges are common animals of most aquatic ecosystems. They utilize flagellated choanocytes to pump water through a series of canals. Incoming water enters through ostia, passes through choanocyte chambers, and exits through the osculum. Bacteria are filtered from incoming water, and large volumes of water can pass through a sponge in a 24-hour period. Because of their simple morphological construction, many cells come into direct contact with the surrounding water as the sponge pumps.

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  • High-molecular-mass PC complexes (PC-HMWCs) constituted by phyto-chelatins (PCs), cadmium and sulfide are synthesized by several organisms after exposure to cadmium. In this study, PC-HMWCs were isolated from photoheterotrophicEuglena gracilisand purified to homogeneity, resulting in compounds of molecular mass 50–380 kDa depending on the CdCl2and sulfate concentrations in the culture medium.

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  • Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: Molecular understanding of sterically controlled compound release through an engineered channel protein (FhuA)

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  • Copper fungicides are environmentally unfriendly. They are very toxic to fish and aquatic invertebrates, such as crab, shrimp and oysters. There are cases where most animal life in soil, including large earthworms, have been eliminated by the extensive use of copper-containing fungicides in orchards. It is strongly bioaccumulated and is very persistent. Once a soil is contaminated with copper, there is no practical way to remove it. The organic insecticide rotenone has been found to be toxic to pigs, rats and dogs and is is very toxic to fish. It causes skin and eye irritations.

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  • Most drugs against malaria that are available or under development target a single process of the parasite infective cycle, favouring the appearance of resistant mutants which are easily spread in areas under chemotherapeutic treatments.

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  • The metallo-b-lactamase (MBL) GOB-1 was expressed via a T7 expression system in Escherichia coliBL21(DE3). The MBL was purified to homoge-neity and shown to exhibit a broad substrate profile, hydrolyzing all the tested b-lactam compounds efficiently.

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  • Lactococcus lactiscan decrease the redox potential at pH 7 (Eh7) from 200 to )200 mV in oxygen free Man–Rogosa–Sharpe media. Neither the con-sumption of oxidizing compounds or the release of reducing compounds during lactic acid fermentation were involved in the decrease inEh7by the bacteria.

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  • Haem (protohaem IX) analogues are toxic compounds and have been con-sidered for use as antibacterial agents, but the primary mechanism behind their toxicity has not been demonstrated. Using the haem protein catalase in the Gram-positive bacterium Enterococcus faecalisas an experimental system, we show that a variety of haem analogues can be taken up by bac-terial cells and incorporated into haem-dependent enzymes.

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  • Sodium 2-propenyl thiosulfate, a water-soluble organo-sulfane sulfur com-pound isolated from garlic, induces apoptosis in a number of cancer cells. The molecular mechanism of action of sodium 2-propenyl thiosulfate has not been completely clarified. In this work we investigated, byin vivo and in vitro experiments, the effects of this compound on the expression and activity of rhodanese.

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  • Phthiocerol dimycocerosates and related compounds are important mole-cules in the biology of Mycobacterium tuberculosis, playing a key role in the permeability barrier and in pathogenicity. Both phthiocerol dimyco-cerosates, the major compounds, and phthiodiolone dimycocerosates, the minor constituents, are found in the cell envelope ofM. tuberculosis, but their specific roles in the biology of the tubercle bacillus have not been established yet.

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