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  • *Light  (2)
  • Burkard sporetrap  (2)
  • Computer Programming and Software  (2)
  • Key words Metallothionein  (2)
  • 1995-1999  (8)
Collection
Keywords
Publisher
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Kinetics of reversible N-ethylmaleimide alkylation of metallothionein and the subsequent metal release (1997)
    Springer
    JBIC 2 (1997), S. 65-73 
    Details
    ISSN: 1432-1327
    Keywords: Key words Metallothionein ; N-Ethylmaleimide ; Alkylation ; Kinetics and mechanism ; 111Cd-NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract  The model alkylating agent N-ethylmaleimide (NEM) reacts reversibly at the metal-bound thiolates of Zn7MT and Cd7MT. An unprecedented feature of this reaction is that it approaches equilibrium and requires a large excess of NEM (〉1 mM for 3 μM protein) to drive it to completion. The complex kinetics of the reaction can be followed by monitoring the release of bound metal ions using the metallochromic dyes Zincon (ZI) for Zn7MT and pyridylazoresorcinol for Cd7MT. An initial lag phase is followed by more rapid release of zinc ions. The observed pseudo-first-order rate constants for the two phases are independent of the ZI and Zn7MT concentrations. The complex NEM concentration dependence of each phase, k f, obs=k f 1+k f 2 [NEM] and k s, obs=k s 1+k s 2 [NEM], demonstrates that the forward reactions are second order and the reverse reactions are first order. The alkylation can be reversed using 2-mercaptoethanol to compete for the protein-bound NEM and regenerate the Zn-binding capability of alkylated MT. An explanation of these observations, based on the reversibility of cysteine alkylation by NEM, was developed and tested. The reactions of Cd7MT are less complete than those of Zn7MT and occur more slowly. 111Cd-NMR studies of the partially alkylated 111Cd7MT reveal that reaction with only four equivalents of NEM completely alters the cluster structure and eliminates the spectral signatures of the α and β clusters, although very little cadmium has been removed from the protein. This finding substantiates the proposed kinetic intermediate, a partially alkylated MT with complete or nearly complete retention of the metal ions, and rules out the possibility of cooperative reactions at either cluster.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007750050107
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Characterization of the cadmium complex of peptide 49–61: a putative nucleation center for cadmium-induced folding in rabbit liver metallothionein IIA (1999)
    Springer
    JBIC 4 (1999), S. 495-507 
    Details
    ISSN: 1432-1327
    Keywords: Key words Metallothionein ; Peptide-metal complexes ; 111Cd NMR ; Protein folding ; Molecular mechanics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract  The synthetic peptide fragment containing residues 49–61 of rabbit liver metallothionein II (MT-II) (Ac-Ile-Cys-Lys-Gly-Ala-Ser-Asp-Lys-Cys-Ser-Cys-Cys-Ala-COOH), which includes the only sequential four cysteines bound to the same metal ion in Cd7MT, forms a stable, monomeric Cd-peptide complex with 1 : 1 stoichiometry (Cd:peptide) via Cd-thiolate interactions. This represents the first synthesis of a single metal-binding site of MT independent of the domains. The 111Cd NMR chemical shift at 716 ppm indicates that the 111Cd2+ in the metal site is terminally coordinated to four side-chain thiolates of the cysteine residues. The pH of half dissociation for this Cd-peptide derivative, ∼3.3, demonstrates an affinity similar to that for Cd7MT. Molecular mechanics calculations show that the thermodynamically most stable folding for this isolated Cd2+ center has the same counterclockwise chirality (Λ or S) observed in the native holo-protein. These properties are consistent with its proposed role as a nucleation center for cadmium-induced protein folding. However, the kinetic reactivity of the CdS4 structure toward 5,5′-dithiobis(5-nitrobenzoate) (DTNB) and EDTA is greatly increased compared to the complete cluster (α-domain or holo-protein). The rate law for the reaction with DTNB is rate=(k uf +k 1,f +k 2,f [DTNB])[peptide], where k uf=0.15 s–1, k 1,f=2.59×10–3 s–1, and k 2,f=0.88 M–1 s–1. The ultrafast step (uf), observable only by stopped-flow measurement, is unprecedented for mammalian (M7MT) and crustacean (M6MT) holo-proteins or the isolated domains. The accommodation of other metal ions by the peptide indicates a rich coordination chemistry, including stoichiometries of M-peptide for Hg2+, Cd2+, and Zn2+, M2-peptide for Hg2+ and Au+, and (Et3PAu)2-peptide.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007750050335
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Sampling in aerobiology. Differences between traverses along the length of the slide in Hirst sporetraps (1996)
    Springer
    Aerobiologia 12 (1996), S. 161-166 
    Details
    ISSN: 1573-3025
    Keywords: Aerobiology ; Methodology ; Sampling error ; Burkard sporetrap
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two years of data from four longitudinal traverses along each day's slide prepared from a continuously running Burkard sporetrap have been analyzed statistically. Using the Friedman test, a statistically significant difference was found between the four traverses, with a greater than 7% loss of pollen grains in the two outer traverses in relation to the inner. Four slides were then selected for more detailed analysis, using 18 longitudinal traverses with a 1-mm separation from the upper to the lower edge of the Melinex tape. There was found to be a progressive decline from the centre to the outside, and more than 4% of pollen grains were found outside the typical 14 mm width of the impaction orifice. There was no correlation between pollen grain size and the decline in counts from the centre to the outside. For the complete data set, there was a general rise in the diversity of bollen types with increasing sample counts, but above about 1000 pollen grains per sample there were no more than 27 pollen types found, often even fewer. A discussion is presented of whether four traverses really should be a fixing sample size, or whether it might be better to fix the total pollen count beginning with a traverse in the middle of the slide and ending with a variable number of traverses when that count is reached.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02447407
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  • 4
    Electronic Resource
    Electronic Resource
    Sampling in aerobiology. Differences between traverses along the length of the slide in Hirst sporetraps (1996)
    Springer
    Aerobiologia 12 (1996), S. 161-166 
    Details
    ISSN: 1573-3025
    Keywords: Aerobiology ; Methodology ; Sampling error ; Burkard sporetrap
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two years of data from four longitudinal traverses along each day's slide prepared from a continuously running Burkard sporetrap have been analyzed statistically. Using the Friedman test, a statistically significant difference was found between the four traverses, with a greater than 7% loss of pollen grains in the two outer traverses in relation to the inner. Four slides were then selected for more detailed analysis, using 18 longitudinal traverses with a 1-mm separation from the upper to the lower edge of the Melinex tape. There was found to be a progressive decline from the centre to the outside, and more than 4% of pollen grains were found outside the typical 14 mm width of the impaction orifice. There was no correlation between pollen grain size and the decline in counts from the centre to the outside. For the complete data set, there was a general rise in the diversity of pollen types with increasing sample counts, but above about 1000 pollen grains per sample there were no more than 27 pollen types found, often even fewer. A discussion is presented of whether four traverses really should be a fixing sample size, or whether it might be better to fix the total pollen count beginning with a traverse in the middle of the slide and ending with a variable number of traverses when that count is reached.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02248144
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  • 5
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    Regulation of the mammalian pineal by non-rod, non-cone, ocular photoreceptors (1999)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1999-04-16
    Description: In mammals, ocular photoreceptors mediate an acute inhibition of pineal melatonin by light. The effect of rod and cone loss on this response was assessed by combining the rd mutation with a transgenic ablation of cones (cl) to produce mice lacking both photoreceptor classes. Despite the loss of all known retinal photoreceptors, rd/rd cl mice showed normal suppression of pineal melatonin in response to monochromatic light of wavelength 509 nanometers. These data indicate that mammals have additional ocular photoreceptors that they use in the regulation of temporal physiology.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lucas, R J -- Freedman, M S -- Munoz, M -- Garcia-Fernandez, J M -- Foster, R G -- New York, N.Y. -- Science. 1999 Apr 16;284(5413):505-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology, Sir Alexander Fleming Building, Imperial College of Science, Technology and Medicine, London, SW7 2AZ, UK. r.j.lucas@ic.ac.uk〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10205062" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Biological Clocks/physiology ; Circadian Rhythm/*physiology ; Cryptochromes ; Darkness ; *Drosophila Proteins ; *Eye Proteins ; Flavoproteins/genetics/physiology ; *Light ; Light Signal Transduction ; Melatonin/*metabolism ; Mice ; Mice, Inbred C3H ; Mice, Transgenic ; *Photoreceptor Cells, Invertebrate ; Photoreceptor Cells, Vertebrate/*physiology ; Pineal Gland/*metabolism ; Receptors, G-Protein-Coupled ; Retina/cytology/*physiology ; Retinal Ganglion Cells/physiology ; Retinal Pigments/genetics/physiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 6
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    Regulation of mammalian circadian behavior by non-rod, non-cone, ocular photoreceptors (1999)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1999-04-16
    Description: Circadian rhythms of mammals are entrained by light to follow the daily solar cycle (photoentrainment). To determine whether retinal rods and cones are required for this response, the effects of light on the regulation of circadian wheel-running behavior were examined in mice lacking these photoreceptors. Mice without cones (cl) or without both rods and cones (rdta/cl) showed unattenuated phase-shifting responses to light. Removal of the eyes abolishes this behavior. Thus, neither rods nor cones are required for photoentrainment, and the murine eye contains additional photoreceptors that regulate the circadian clock.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Freedman, M S -- Lucas, R J -- Soni, B -- von Schantz, M -- Munoz, M -- David-Gray, Z -- Foster, R -- New York, N.Y. -- Science. 1999 Apr 16;284(5413):502-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology, Alexander Fleming Building, Imperial College of Science, Technology and Medicine, London, SW7 2AZ, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10205061" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Biological Clocks/*physiology ; Circadian Rhythm/*physiology ; *Light ; Mice ; Mice, Transgenic ; Motor Activity ; *Ocular Physiological Phenomena ; Photoreceptor Cells, Vertebrate/*physiology ; Pigments, Biological/physiology ; Retinal Cone Photoreceptor Cells/physiology ; Retinal Pigments/physiology ; Retinal Rod Photoreceptor Cells/physiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 7
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    Dependent Types and Explicit Substitutions (1999)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: We present a dependent-type system for a lambda-calculus with explicit substitutions. In this system, meta-variables, subject reduction, soundness, confluence and weak normalization.
    Keywords: Computer Programming and Software
    Type: NASA/CR-1999-209722 , NAS 1.26:209722 , ICASE-99-43
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 8
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    Structural Embeddings: Mechanization with Method (1999)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: The most powerful tools for analysis of formal specifications are general-purpose theorem provers and model checkers, but these tools provide scant methodological support. Conversely, those approaches that do provide a well-developed method generally have less powerful automation. It is natural, therefore, to try to combine the better-developed methods with the more powerful general-purpose tools. An obstacle is that the methods and the tools often employ very different logics. We argue that methods are separable from their logics and are largely concerned with the structure and organization of specifications. We, propose a technique called structural embedding that allows the structural elements of a method to be supported by a general-purpose tool, while substituting the logic of the tool for that of the method. We have found this technique quite effective and we provide some examples of its application. We also suggest how general-purpose systems could be restructured to support this activity better.
    Keywords: Computer Programming and Software
    Type: NASA/CR-1999-209360 , NAS 1.26:209360 , ICASE-99-26
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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