Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:6.2.1.1 (ACS)
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In order to assess the extent to which metabolism within the sheep placenta may influence the transfer of metabolites between mother and foetus at different stages of gestation the activities of enzymes concerned with some aspects of carbohydrate, amino acid and keton body metabolism were determined in placental cotyledons resected from ewes during the last three months of pregnancy. The activities of pyruvate kinase (EC 2.7.1.40), lactate dehydrogenase (EC 1.1.1.27), malate dehydrogenase (EC 1.1.1.37), ATP citrate (pro-3S)-lyase (EC 4.1.3.8), citrate (si)-synthase (EC 4.1.3.7), acetyl-CoA synthetase (EC 6.2.1.1), acetyl-CoA acetyltransferase (EC 2.3.1.9) and 3-keto acid CoA-transferase (EC 2.8.3.5) per gram wet weight cotyledon do not change during the period studied. The activities of alanine aminotransferase (EC 2.6.1.2), aspartate aminotransferase (EC 2.6.1.1), isocitrate dehydrogenase (NADP+) (EC 1.1.1.42), ornithine-oxoacid aminotransferase (EC 2.6.1.13) and 3-hydroxybutyrate dehydrogenase (EC 1.1.1.30) show an increase in activity between the third and fourth months of pregnancy whilst the activities of arginase (EC 3.5.3.1) and possibly pyruvate carboxylase (EC 6.4.1.1) show an increase in activity between the fourth and final months of pregnancy. Ornithine decarboxylase (EC 4.1.1.17) activity declines to one tenth of its activity during this later period. The absence of detectable activities of phosphoenolpyruvate carboxykinase (EC 4.1.1.32) and ornithine carbamoyltransferase (EC 2.1.3.3) indicate that gluconeogenesis and urea synthesis from ammonia do not occur in the sheep placenta. It appears that the ability of the placenta to metabolise several substrates is achieved by the time the placenta reaches its maximum size at approximately 90 days.
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PMID:Enzyme activities in the sheep placenta during the last three months of pregnancy. 84 73

Halophilic archaea activate acetate via an (acetate)-inducible AMP-forming acetyl-CoA synthetase (ACS), (Acetate+ATP+CoA --> Acetyl-CoA+AMP+PP(i)). The enzyme from Haloarcula marismortui was purified to homogeneity. It constitutes a 72-kDa monomer and exhibited a temperature optimum of 41 degrees C and a pH optimum of 7.5. For optimal activity, concentrations between 1 M and 1.5 M KCl were required, whereas NaCl had no effect. The enzyme was specific for acetate (100%) additionally accepting only propionate (30%) as substrate. The kinetic constants were determined in both directions of the reaction at 37 degrees C. Using the N-terminal amino acid sequence an open reading frame - coding for a 74 kDa protein - was identified in the partially sequenced genome of H. marismortui. The function of the ORF as acs gene was proven by functional overexpression in Escherichia coli. The recombinant enzyme was reactivated from inclusion bodies, following solubilization in urea and refolding in the presence of salts, reduced and oxidized glutathione and substrates. Refolding was dependent on salt concentrations of at least 2 M KCl. The recombinant enzyme showed almost identical molecular and catalytic properties as the native enzyme. Sequence comparison of the Haloarcula ACS indicate high similarity to characterized ACSs from bacteria and eukarya and the archaeon Methanosaeta. Phylogenetic analysis of ACS sequences from all three domains revealed a distinct archaeal cluster suggesting monophyletic origin of archaeal ACS.
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PMID:AMP-forming acetyl-CoA synthetase from the extremely halophilic archaeon Haloarcula marismortui: purification, identification and expression of the encoding gene, and phylogenetic affiliation. 1594 65

Traditional small-molecule fluorophores are always fluorescent. This attribute can obscure valuable information in biological experiments. Here, we report on a versatile "latent" fluorophore that overcomes this limitation. At the core of the latent fluorophore is a derivative of rhodamine in which one nitrogen is modified as a urea. That modification enables rhodamine to retain half of its fluorescence while facilitating conjugation to a target molecule. The other nitrogen of rhodamine is modified with a "trimethyl lock", which enables fluorescence to be unmasked fully by a single user-designated chemical reaction. An esterase-reactive latent fluorophore was synthesized in high yield and attached covalently to a cationic protein. The resulting conjugate was not fluorescent in the absence of esterases. The enzymatic activity of esterases in endocytic vesicles and the cytosol educed fluorescence, enabling the time-lapse imaging of endocytosis into live human cells and thus providing unprecedented spatiotemporal resolution of this process. The modular design of this "fluorogenic label" enables the facile synthesis of an ensemble of small-molecule probes for the illumination of numerous biochemical and cell biological processes.
ACS Chem Biol 2006 May 23
PMID:Fluorogenic label for biomolecular imaging. 1716 79

Enthused by the fascinating properties of graphene, we have prepared graphene analogues of BN by a chemical method with a control on the number of layers. The method involves the reaction of boric acid with urea, wherein the relative proportions of the two have been varied over a wide range. Synthesis with a high proportion of urea yields a product with a majority of 1-4 layers. The surface area of BN increases progressively with the decreasing number of layers, and the high surface area BN exhibits high CO(2) adsorption, but negligible H(2) adsorption. Few-layer BN has been solubilized by interaction with Lewis bases. We have used first-principles simulations to determine structure, phonon dispersion, and elastic properties of BN with planar honeycomb lattice-based n-layer forms. We find that the mechanical stability of BN with respect to out-of-plane deformation is quite different from that of graphene, as evident in the dispersion of their flexural modes. BN is softer than graphene and exhibits signatures of long-range ionic interactions in its optical phonons. Finally, structures with different stacking sequences of BN have comparable energies, suggesting relative abundance of slip faults, stacking faults, and structural inhomogeneities in multilayer BN.
ACS Nano 2010 Mar 23
PMID:Graphene analogues of BN: novel synthesis and properties. 2012 1

Controlling the morphological evolution in nanostructures is essential for improving their functionality, for example, in catalysis. Here, we demonstrate, using chromium oxide as a model system, that morphologies of functional binary oxide particles can be tailored by an efficient template-free synthetic approach. We construct a morphological "phase diagram" for chromium oxide spheres that shows the evolution of size and surface roughness as a function of the precursor and urea concentrations. It is notable that these chromium oxide spheres show an exceptional ability to remove azo-dye pollutant in water treatment. Thus, the porous chromium oxide spheres with very good dye absorptions are expected to be useful in alternative absorption technologies.
ACS Appl Mater Interfaces 2009 Sep
PMID:Three-dimensional morphology control during wet chemical synthesis of porous chromium oxide spheres. 2035 17

TiO2 thin films are highly stable and can be deposited onto a wide variety of substrate materials under moderate conditions. We demonstrate that organic alkenes will graft to the surface of TiO2 when illuminated with UV light at 254 nm and that the resulting layers provide a starting point for the preparation of DNA-modified TiO2 thin films exhibiting excellent stability and biomolecular selectivity. By using alkenes with a protected amino group at the distal end, the grafted layers can be deprotected to yield molecular layers with exposed primary amino groups that can then be used to covalently link DNA oligonucleotides to the TiO2 surface. We demonstrate that the resulting DNA-modified surfaces exhibit excellent selectivity toward complementary versus noncomplementary target sequences in solution and that the surfaces can withstand 25 cycles of hybridization and denaturation in 8.3 M urea with little or no degradation. Furthermore, the use of simple masking methods provides a way to directly control the spatial location of the grafted layers, thereby providing a way to photopattern the spatial distribution of biologically active molecules to the TiO2 surfaces. Using Ti films ranging from 10 to 100 nm in thickness allows the preparation of TiO2 films that range from highly reflective to almost completely transparent; in both cases, the photochemical grafting of alkenes can be used as a starting point for stable surfaces with good biomolecular recognition properties.
ACS Appl Mater Interfaces 2009 May
PMID:Photochemical grafting and patterning of biomolecular layers onto TiO2 thin films. 2035 86

Nanosized boron(III) oxide-doped titania was prepared by homogeneous hydrolysis of titanium oxo-sulfate with urea in aqueous solutions in the presence of amorphous boron. The prepared samples were annealing at 700 degrees C. The structure of as-prepared samples was characterized by X-ray powder diffraction (XRD) and selected area electron diffraction (SAED) and surface area (BET) and porosity determination (BJH). The morphology and microstructure characteristics were obtained by scanning electron microscopy (SEM) and high-resolution electron microscopy (HRTEM). The method of UV/vis diffuse reflectance spectroscopy was employed to estimate band gap energies of the boron-doped titania. The photoactivity of the prepared samples was assessed by the photocatalytic decomposition of Orange II dye in an aqueous slurry during irradiation at 365 and 400 nm wavelength. The prepared titania samples doped with boron(III) oxide showed better photocatalytic activity in comparison with the reference TiO(2) sample. These photocatalysts showed better photocatalytic performance under visible-light irradiation.
ACS Appl Mater Interfaces 2010 Feb
PMID:Photocatalytic activity of boron-modified titania under UV and visible-light illumination. 2035 7

Continuous nickel oxide (NiO) nanocomposite layer on flexible polyimide (PI) substrate was prepared via an ion exchange technique. First, nickel(Pi) poly(amate) layers were formed on both surfaces of PI film through chemical surface modification of PI films in aqueous NaOH solution and then ion exchange in aqueous NiSO4 solution. Subsequently, hydrothermal treatment of the Ni2+-loaded PI films in an aqueous urea solution led to Ni(OH)2 formation in the surface-modified layers. Final thermal annealing in ambient air made Ni(OH)2 decompose to NiO, which diffused and aggregated to give continuous layers on both surfaces of PI film. The composite films were characterized by XRD, XPS, SEM, TEM, TGA, and DSC, respectively. Results from SEM and TEM measuring revealed that the NiO layers consisted of NiO nanoparticles with diameter ranging from 10 to 15 nm. Thermal properties of PI/NiO nanocomposite films were similar to those of host PI. This paper provides an effective methodology for the preparation of polymer/metal oxide nanocomposite films, which hold great promise toward the potential application in the areas of flexible microsensors and devices.
ACS Appl Mater Interfaces 2010 Jan
PMID:Fabrication of nickel oxide nanocomposite layer on a flexible polyimide substrate via ion exchange technique. 2035 27

Double-walled polyurethane/poly(urea-formaldehyde) microcapsules (PU/UF) are prepared for use in self-healing materials. This modified encapsulation procedure combines two chemistries to form more robust capsule shell walls in a single operation. Robust capsules are formed by this procedure as long as the aromatic polyisocyanate prepolymer is soluble in the core liquid and the core liquid is compatible with isocyanates. Compared to a standard UF encapsulation, the modified procedure results in capsules with an increase in shell wall thickness from 200 to 675 nm as a function of the amount of PU added to the core liquid. Thermal stability of PU/UF microcapsules prepared with varying amounts of PU is compared to UF microcapsules. Mechanical properties of the PU/UF microcapsules are assessed from single-capsule compression testing.
ACS Appl Mater Interfaces 2010 Apr
PMID:Robust, double-walled microcapsules for self-healing polymeric materials. 2042 39

Superparamagnetic nanoparticles are of great current interest for biomedical applications in both diagnostics and treatment. Magnetic nanoparticles (MNP) can be manipulated by magnetic fields, so that when functionalized, they can be used for the purification and separation of biomolecules and even whole cells. Here we report combining the separation capabilities of MNPs with the functional (binding) capability of molecularly imprinted polymers. Albumin- creatinine-, lysozyme-, and urea-imprinted polymer nanoparticles were synthesized from poly(ethylene-co-ethylene alcohol) via phase inversion, with both target molecules and hydrophobic magnetic nanoparticles mixed within the polymer solution. Several ethylene:ethylene alcohol mole ratios were studied. The rebinding capacities for those three target molecules varied from 0.76 +/- 0.02 to 5.97 +/- 0.04 mg/g of molecularly imprinted magnetic nanoparticles. Lastly, the composite nanoparticles were used for separation and sensing of template molecules (e.g., human serum albumin) in real samples (urine) and results were compared with a commercial ARCHITECT ci 8200 system.
ACS Appl Mater Interfaces 2010 Jun
PMID:Synthesis of magnetic molecularly imprinted poly(ethylene-co-vinyl alcohol) nanoparticles and their uses in the extraction and sensing of target molecules in urine. 2052 74


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