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  • Chemistry  (25)
  • Cell & Developmental Biology  (12)
  • GdIII trigonal prismatic complexes  (1)
  • Wiley-Blackwell  (37)
  • 1
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of copolymers of L-lysine and L-valine [poly(L-lysinef L-valine100-f)] containing 0-13% L-valine have been studied, in 0.10M KF solution, using potentiometric titration and circular dichroism spectroscopy. Incorporation of increasing amounts of valine into the copolymers favors β-sheet formation over α-helix formation at high pH and room temperature. The titrations were analyzed using the method of Zimm and Rice and the partial free energy (ΔG0cβ) for the coil-to-β-sheet transition for valine is estimated at 900 cal/mole at 25°C. From the temperature dependence of the free energy, the partial enthalpy, ΔH0cβ, and entropy, ΔS0cβ, of the transition for valine is estimated to be 854 cal/mole and 6.0 e.u., respectively. The corresponding partial thermodynamic parameters for L-lysine are in agreement with published results. The fraction of β-sheet versus pH has been calculated for poly(L-lysine86.8 L-valine13.2) at 25.0°C using the titration data; data obtained from circular dichroism spectroscopy for the same copolymer are in good accord. It is concluded from these results that L-valine is a very strong β-sheet forming amino acid. Furthermore, these results indicate that the Zimm-Rice method is applicable to transitions between the coil and β-sheet states for a polypeptide containing two different residues.
    Additional Material: 7 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 34 (1994), S. 783-797 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The secondary structure of xanthan in solutions of relatively low salt concentration and at room temperature has been investigated using static light scattering experiments. Additional evidence has been found for a dimeric structure at 25°C in 0.01M NaCl. From the experimental z-average mean square (ms) radius of gyration, a value for the persistence length p has been estimated, taking explicitly into account the polydispersity of the three samples used, which has been established by gel permeation chromatography (GPC) measurements. The experimental particle scattering functions of the three samples are consistent with theoretical estimates for polydisperse systems with the same value of p = 65 ± 10 nm and the molar mass per unit length for a dimeric structure.This secondary structure remains unaffected by the ionic strength in the 0.005-0.0lM range. Partial aggregation seems to occur at higher NaCl concentrations.Light scattering and GPC data show that heating the xanthan 0.01M NaCl solutions to about 70°C considerably reduces the Mw of the low molar mass sample (2.3 × 105-g·mol-1), contrary to what is observed for the high molar mass sample (1.8 × 106-g·mol-1). These experimental findings can be accounted for by a partial temperature-induced dissociation of the xanthan dimers according to an all-or-none mechanism. © 1994 John Wiley & Sons, Inc.
    Additional Material: 14 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 12 (1973), S. 655-674 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ultraviolet absorption, linear dichroism, circular dichroism, and oriented circular dichroism of collagen are reported and the spectra are resolved into a self-consistent set of bands in accord with exciton theory. The parallel band at 200 nm has 40% of the π → π* intensity; the perpendicular band is placed at 189 nm yielding a splitting of 2700 cm-1. The circular dichroism is resolved into two Gaussians at λ∥ and λτ (rotational strengths +14 × 10-40 and -32 × 10-40 esu2. cm2) plus a large non-Gaussian (“helix”) band with ampplitude -25,000° at 201 nm. These data appear to be in reasonably good accord with recent calculations.Measurements of the absorption, linear dichroism and circular dichroism of polyproline I and II are also reported and are resolved into their component bands. Polyproline I is in good accord with exciton theory, whereas polyproline II remains unsatisfactory.
    Additional Material: 11 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 18 (1979), S. 2267-2277 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pinacyanol in the presence of an excess of poly(L-glutamic acid) [polymer/dye ratio (P/D) 〉 10] exhibits different absorption spectra in the visible region when bound to the slightly charged polypeptide in the α-helical conformation or to the nearly completely dissociated polypeptide in the coillike conformation. These spectra reveal aggregation of the dye bound to the macromolecular chain in both conformations, although in the coillike one different kinds of aggregates may be present. Dye binding is accompanied by the appearance of CD bands in the visible region which are also different for the α-helical and the coillike conformations. The aggregates formed in the presence of the latter change slowly in time and seem to induce some conformational changes in the polypeptide chain. Furthermore, they have been found to be, at least partially, stable with respect to a subsequent reversal to the α-helical conformation. All results could be qualitatively interpreted assuming that in the coillike conformation, ordered regions exist along the chain as proposed by Krimm and Tiffany.
    Additional Material: 5 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 127 (1969), S. 383-407 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The structure of human labial salivary gland acini was studied by light and electron microscopy. Contrary to previous reports, these glands were pure mucous in nature; no serous elements were present. The acinar cells were found in all stages of maturation. Immature cells were characterized by an extensive and highly organized rough-surfaced endoplasmic reticulum. The Golgi complex was extremely prominent, consisting of stacks of flattened cisternae and swarms of small vesicles. Mucous droplets were almost completely absent. As secretory activity progressed, the endoplasmic reticulum involuted, while the Golgi cisternae became distended and formed many vacuoles. In mature mucous cells, the apical cytoplasm was filled with membrane-bounded mucous droplets, and the nucleus was displaced basally. The droplets frequently showed great variation in density from cell to cell, and even within the same cell they sometimes were quite heterogeneous. They were liberated from the acinar cells by an apocrine process, so that droplets with intact limiting membranes were often observed in the acinar lumen. These droplets soon lysed, their contents fusing into streams of mucus. Occasionally during apocrine secretion a mucous cell failed to reconstitute its apical surface, and its entire contents spilled into the acinar lumen.Unusual cytoplasmic inclusions were present in many of the acinar cells. These inclusions, which were surrounded by a single membrane, consisted of lipid droplets closely associated with bundles of fine filaments.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 301-302 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 247-255 
    ISSN: 0886-9383
    Keywords: Analysis of variance ; Assumptions ; Graphics ; Models ; Validation of model ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The computer has made it possible to scrutinize data rapidly by means of graphics. This should be done prior to the application of any model to the data, since the model must be validated before using it as a means of analyzing the data. The procedure is illustrated in terms of two examples of real experimental data.
    Additional Material: 5 Ill.
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  • 8
    ISSN: 0886-1544
    Keywords: Ca2+-ATPase of sarcoplasmic reticulum ; immunofluorescence ; myofibers types I (slow) and II (fast) ; II D8 monoclonal antibody ; II H11 monoclonal antibody ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Ca2+ -ATPase of the sarcoplasmic reticulum was localized in cryostat sections from three different adult canine skeletal muscles (gracilis, extensor carpi radialis, and superficial digitalis flexor) by immunofluorescence labeling with monoclonal antibodies to the Ca2+ -ATPase Type I (slow) myofibers were strongly labeled for the Ca2+ -ATPase with a monoclonal antibody (II D8) to the CA2+ -ATPase of canine cardiac sarcoplasmic reticulum; the type II (fast) myofibers were labeled at the level of the background with monoclonal antibody II D8. By contrast, type II (fast) myofibers were strongly labeled for Ca2+ -ATPase of rabbit skeletal sarcoplasmic reticulum. The subcellular distribution of the immunolabeling in type I (slow) myofibers with monoclonal antibody II D8 corresponded to that of the sarcoplasmic reticulum as previously determined by electron microscopy. The structural similarity between the canine cardiac Ca2+ -ATPase present in the sarcoplasmic reticulum of the canine slow skeletal muscle fibers was demonstrated by immunoblotting. Monoclonal antibody (II D8) to the cardiac Ca2+ -ATPase binds to only one protein band present in the extract from either cardiac or type I (slow) skeletal muscle tissue. By contrast, monoclonal antibody (II H11) to the skeletal type II (fast) Ca2+ -ATPase binds only one protein band in the extract from type II (fast) skeletal muscle tissue. These immunopositive proteins coelectrophoresed with the Ca2+ -ATPase of the canine cardiac sarcoplasmic reticulum and showed an apparent Mr of 115,000. It is concluded that the Ca2+ -ATPase of cardiac and type I (slow) skeletal sarcoplasmic reticulum have at least one epitope in common, which is not present on the Ca2+ -ATPase of sarcoplasmic reticulum in type II (fast) skeletal myofibers. It is possible that this site is related to the assumed necessity of the Ca2+ -ATPase of the sarcoplasmic reticulum in cardiac and type I (slow) skeletal myofibers to interact with phosphorylated phospholamban and thereby enhance the accumulation of Ca2+ in the lumen of the sarcoplasmic reticulum following β-adrenergic stimulation.
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  • 9
    ISSN: 0730-2312
    Keywords: electron microscopy ; plasma membrane ; lymphoma cells ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Plasma membrane was isolated from the mouse T lymphoma cell line WEHI-22 using four different methods of cell disruption followed by centrifugal fractionation. Disruption by nitrogen cavitation or by shearing with a cell pump produced plasma membrane vesicles of similar buoyant density (1.10 g/ml) and morphological appearance. Few C-type virus particles were present. Cell disruption with 2% Tween-40 produced membrane vesicles of similar morphology but lower density (1.09 g/ml). All of the above preparations resulted in vesicles with aggregated intramembranous particles after freeze fracture. Microvesiculation with a sublytic concentration of a lysophosphatidylcholine analog (ET-12-H) (0.0032% w/v) produced small membrane vesicles which could be isolated without differential centrifugation. However, these had a slightly higher density than vesicles prepared by cavitation or shearing and were co ntaminated by virus particles. Unlike the other preparations, vesicles prepared with ET-I2-H had dispersed intramembranous particles. The enzyme γ-glutamyl transferase was enriched from 20- to 45-fold in the membrane preparations and proved a suitable plasma membrane marker for these cells whose 5′-nucleotidase content is very low.
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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1313-1313 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No. Abstract.
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