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  • Inorganic Chemistry  (3)
  • Adaptation  (1)
  • Conformational energy calculations  (1)
  • 1
    ISSN: 1432-1017
    Keywords: Conformational energy calculations ; Protein conformation ; Molecular mechanics ; Proteinase inhibitor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Summary The molecular conformation of the basic pancreatic trypsin inhibitor (BPTI) is known in considerable detail from both X-ray studies in single crystals and NMR studies in solution. The NMR experiments showed that the aromatic rings of the phenylalanyl and tyrosyl residues can undergo rapid rotational motions about the Cβ-Cγ bond. The present paper describes a model investigation of the mechanistic aspects of these intramolecular rotational motions. From calculations of the conformational energies for molecular species derived from the X-ray structure by rotations of individual aromatic rings, it was apparent that the rotational motions of the aromatics could only be understood in a flexible structure. Flexibility was simulated by allowing the protein to relax to an energetically favorable conformation for each of the different rotation states of the aromatic rings. It was then of particular interest to investigate how the perturbations caused by different rotation states of the aromatic rings were propagated in the protein structure. It was found that the rotation axes Cβ-Cγ were only slightly affected (Δχ 1≲20°). The most sizeable perturbations are caused by through space interactions with nearby atoms, which move away from the ring center and thus release the steric hindrance opposing the rotational motions. The values for the energy barriers obtained from the energy minimization are of the same order of magnitude as those measured by NMR.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Environmental biology of fishes 33 (1992), S. 153-165 
    ISSN: 1573-5133
    Keywords: Neuroanatomy ; Ecology ; Vision ; Olfaction ; Gustation ; Plasticity ; Adaptation ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The size of seven neural structures was compared in 51 species of Notropis, Pteronotropis, Cyprinella, Luxilus, Lythrurus, and Hybopsis, and related to the turbidity of the species& habitat. This last parameter was assessed for each species by personal communication with 42 ichthyologists. To control for size differences among species, all analyses were performed on the residuals from a regression of each character on standard length. Principal components analysis (PCA) of the residuals produced four significant PC-axes that together explained 65% of the total variation represented in the original variables. The size of brain structures concerned with vision, olfaction, and gustation was correlated with habitat turbidity. Two-way Analyses of Covariance (ANCOVAs) revealed significant differences between species in the size of all structures. Sexual dimorphism was found in the size of the olfactory bulb and the cerebellum, and significant two-way interactions (species vs. sex) were detected for the telencephalon, optic lobes, cerebellum, vagal lobe, and the eye. Cluster analysis indicated that neither similar turbidity preference nor shared phylogeny is alone sufficient to explain the observed differences in brain morphology.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 98 (1965), S. 2353-2360 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Eine eingehende Analyse der diffusen Röntgenstreuung am Ecdyson beweist für das Insektenhormon ein Perhydrophenanthren- bzw. Sterin-Grundgerüst und gestattet die Bestimmung der Orientierung dieses Grundgerüstes im Kristall.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 96 (1963), S. 1712-1719 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Verschiedene Umsetzungen am reinen syn-Methyldiazotat-kalium in festem Zustand lassen eine Nitrosaminstruktur vermuten. Kernresonanzmessungen beweisen lediglich das Vorhandensein einer CH3-Gruppe. Die Röntgenstrukturanalyse ergibt das Vorliegen eines mesomeren organischen Anions mit cis-Konfiguration, dessen N—N—O-Bindungen annähernd gleichen, ca. 50-proz. Doppelbindungscharakter haben und das dem Kaliumkation als Ganzes gegenübersteht.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 98 (1965), S. 2403-2424 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Die vollständige Struktur und Konfiguration des Insektenverpuppungshormons Ecdyson wird durch Röntgenstrukturanalyse der natürlichen, schweratomfreien Verbindung als 2β.3β.14α.22βF.25-Pentahydroxy-Δ7-5β-cholestenon-(6) ermittelt.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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