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  • 1
    Unknown
    Charlottesville, Va : University of Virginia Library
    Keywords: African Americans, Suffrage, History.
    ISBN: 0-585-20369-5
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  • 2
    Unknown
    Champaign, Ill : Project Gutenberg
    Keywords: Sri Lanka, Description and travel.
    ISBN: 0-585-06948-4
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  • 3
    ISSN: 1432-1327
    Keywords: Metal substitution Cerium binding Lactoferrin Crystal structure Transferrin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract. Proteins of the transferrin family play a key role in iron homeostasis through their extremely strong binding of iron, as Fe3+. They are nevertheless able to bind a surprisingly wide variety of other metal ions. To investigate how metal ions of different size, charge and coordination characteristics are accommodated, we have determined the crystal structure of human lactoferrin (Lf) complexed with Ce4+. The structure, refined at 2.2 Å resolution (R=20.2%, R free=25.7%) shows that the two Ce4+ ions occupy essentially the same positions as do Fe3+, and that the overall protein structure is unchanged; the same closed structure is formed for Ce2Lf as for Fe2Lf. The larger metal ion is accommodated by small shifts in the protein ligands, made possible by the presence of water molecules adjacent to each binding site. The two Ce4+ sites are equally occupied, indicating that the known difference in the pH-dependent release of Ce4+ arises from a specific protonation event, possibly of the His ligand in one of the binding sites. Comparing the effects of binding Ce4+ with those for the binding of other metal ions, we conclude that the ability of transferrins to accommodate metal ions other than Fe3+ depends on an interplay of charge, size, coordination and geometrical preferences of the bound metal ion. However, it is the ability to accept the six-coordinate, approximately octahedral, site provided by the protein that is of greatest importance.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Human bile-salt dependent lipase (BSDL), secreted into both the digestive tract and human milk, is integral to the effective absorption of dietary lipids. In attempts to obtain crystals suitable for high-resolution X-ray crystallographic studies, various forms of the enzyme have been crystallized, including native and desialidated human milk BSDL and both intact recombinant BSDL and a truncated form lacking the heavily glycosylated C-terminal repeat region. Trigonal crystals of native BSDL, with unit-cell parameters a = b = 90.0, c = 156.1 Å, were obtained using 15–20%(w/v) PEG 8000 as precipitant. These crystals diffract to 3.5 Å along the unique axis, but to only 5–7 Å in orthogonal directions. Crystals of recombinant truncated BSDL grown from 15–20%(w/v) PEG 6000 are orthorhombic, space group P212121, with unit-cell parameters a = 59.2, b = 90.0, c = 107.7 Å, and diffract to 2.6 Å resolution. These are suitable for structural analysis by X-ray crystallography.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1572-9591
    Keywords: Fusion energy ; international collaboration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract This report was prepared by a Working Group at the request of the U.S. Department of Energy, Office of Fusion Energy Sciences in 1997. The report addresses technical opportunities for mutually beneficial collaboration between the United States and other international fusion research programs. A number of outstanding opportunities are discussed.
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  • 6
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The effects of pressure and oxygen fugacity (fO2) on trace element partitioning between pargasitic amphibole and alkali-basaltic melts have been determined at pressures from 1.5 to 2.5 GPa and oxygen fugacities at 2 log units above and below the nickel–nickel oxide buffer. Amphibole crystallization experiments were performed in a piston cylinder apparatus and partition coefficients between amphibole and quenched melt of large-ion-lithophile elements (LILE: Rb, Sr, Ba), high-field-strength elements (HFSE: Zr, Nb, Ta, Hf, U, Th) and rare-earth elements (REE: La to Lu; +Y) were measured with a LASER ablation inductively coupled plasma – mass spectrometer. Increasing pressure from 1.5 to 2.5 GPa at similar temperatures and approximately constant fO2 increases D Rb but decreases D Zr and D Hf and D REE (D La, D Ce, D Pr). An empirical relationship was observed between D Zr and (Ti/Al)M2 in the amphibole, which can be described by: Increasing the fO2 by ∼4 log units (∼NNO–2.0 to ∼NNO+2.2) at similar temperatures and constant pressure increases D Ba and D Nd but decreases D Ti. An increase in pressure or fO2 decreases the maximum partition coefficient (D o ), the Young's modulus (E) and the optimum ionic radius (r o ) of the A-, M2- and M4-lattice sites. The calculated r o values from the monovalent cations (Na, K, Rb) in the A site and the quadrivalent cations (Ti, Hf, Zr) in the M2 lattice sites suggests that amphiboles crystallized from alkaline basalt material have smaller 〈A-O〉 and 〈M2-O〉, mean bond-lengths than those formed from pargasitic materials at identical pressures and fO2's. The measured partition coefficients were used to calculate trace element concentrations in melts formed by partial melting of amphibole-bearing peridotite. This modeling demonstrates those changes in either the pressure or fO2 of melting can exert a significant effect on Rb/HFSE ratios in the melts and thus help explain the wide variations of these ratios sometimes observed in basaltic rock suites.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-1009
    Keywords: KEY WORDS: Reservoir; First Nations; Dust control; Native vegetation; Integrated resource management
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1420-9071
    Keywords: Key words. HIV-1; Tat; metastasis; TIP30; CC3.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Human TIP30 is a cofactor that specifically enhances human immunodeficiency virus-1 (HIV-1) Tat-activated transcription. The sequence of TIP30 is identical to that of CC3, a protein associated with metastasis suppression. TIP30/CC3 is a member of the short-chain dehydrogenases/reductases (SDR) family. Of the several experimentally determined SDR structures, Escherichia coli uridine diphosphate (UDP) galactose-4 epimerase is most similar to TIP30/CC3. Because the direct sequence similarity between TIP30/CC3 and E. coli UDP galactose-4 epimerase is low, we used the transitive nature of homology and employed two Aquifex aeolicus proteins as intermediaries in the homology modeling process. Comparison of our structural model with that of known SDRs reveals that TIP30/CC3 contains several well-conserved features, including a βαβ fold at the amino terminus, which we predict binds NADP(H). TIP30/CC3 contains characteristic motifs at the catalytic site of SDRs, including a serine, tyrosine, and lysine that are important in catalyzing hydride transfer between substrate and cofactor. We also predict that a unique 20-amino acid sequence found at the amino terminus is an α-helix. Because this region contains several positively and negatively charged amino acids, it may dock TIP30/CC3 to other proteins. Our structural model points to this α-helix and the SDR-like part of TIP30/CC3 for mutagenesis experiments to elucidate its role in HIV-1 Tat-activated transcription, metastasis suppression, and other cellular functions.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1423-0127
    Keywords: Phosphatidylethanol ; Phosphatidic acid ; Ethanol ; Phospholipase A2, cytosolic ; Phospholipase D ; RAW 264.7 cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The synthesis of inflammation mediators produced from arachidonic acid is regulated primarily by the cellular concentration of free arachidonic acid. Since intracellular arachidonic acid is almost totally present as phospholipid esters, the concentration of intracellular arachidonic acid is primarily dependent on the balance between the release of arachidonic acid from membrane phospholipids and are uptake of arachidonic acid into membrane phospholipids. Cytosolic phospholipase A2 is a calcium-dependent enzyme that catalyzes the stimulus-coupled hydrolysis of arachidonic acid from membrane phospholipids. Following exposure of macrophages to various foreign or endogenous stimulants, cytosolic phospholipase A2 is activated. Treatment with these compounds may also stimulate phospholipase D activity, and, in the presence of ethanol, phospholipase D catalyzes the synthesis of phosphatidylethanol. A cell-free system was used to evaluate the effect of phosphatidylethanol on cytosolic phospholipase A2 activity. Phosphatidylethanol (0.5 µM) added to 1-stearoyl-2-[3H]-arachidonoyl-sn-glycero-3-phosphocholine vesicles stimulated cytosolic phospholipase A2 activity. However, high concentrations (20–100 µM) of phosphatidylethanol inhibited cytosolic phospholipase A2 activity. Phosphatidic acid, the normal phospholipase D product, also stimulated cytosolic phospholipase A2 activity at 0.5 µM, but had an inhibitory effect on cytosolic phospholipase A2 activity at concentrations of 50 and 100 µM. Ethanol (20–200 mM), the precursor of phosphatidylethanol, added directly to the assay did not alter cytosolic phospholipase A2 activity. These results suggest that phosphatidylethanol alters the physical properties of the substrate, and at lower concentrations of anionic phospholipids the substrate is more susceptible to hydrolysis. However, at high concentrations, phosphatidylethanol either reverses the alterations in physical properties of the substrate or phosphatidylethanol may be competing as the substrate. Both interactions may result in lower cytosolic phospholipase A2 activity.
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  • 10
    ISSN: 1435-5957
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geography , Economics
    Notes: Abstract. The supermarket equation is a differential equation peculiar to spatial science. The complex form of this equation is presented here and is used to study aggregate consumer shopping patterns. The focus is the relationship between trips to, and shopping within, planned shopping centres relative to retail trading hour boundaries. In this context, five malls in Sydney are studied in the period prior to the introduction of deregulated shopping hours in 1992. The space-time convergence of aggregate consumer behaviour at these retail nodes show that the gravity coefficient can be treated in a temporal context. Estimates of mean trading hours can be made from the general solution and these are compared to alternative estimates from Fourier analysis. Time corrections to the gravity coefficient allow for a dynamic market area analysis, where the primary trade area can be determined relative to the trading hours of the shopping centre. A Sydney example shows how this methodology can be applied with population census data.
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