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  • 1995-1999  (2)
  • CPG  (1)
  • Heme-containing enzyme  (1)
  • Magnetic circular dichroism  (1)
  • 1
    Electronic Resource
    Electronic Resource
    The neuroethology of sound production in tiger moths (Lepidoptera, Arctiidae) (1995)
    Springer
    Journal of comparative physiology 176 (1995), S. 541-549 
    Details
    ISSN: 1432-1351
    Keywords: Moth ; Transection ; CPG ; Tymbal ; Ganglia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract When stimulated either acoustically or tactually, certain species of arctiid moths rhythmically emit trains of clicks from metathoracic tymbals. The purpose of the experiments presented here was to determine the location within the central nervous system (CNS) of the proposed tymbal central pattern generator (CPG) in Cycnia tenera. Motor neuron impulses that underlie tymbal activation were recorded extracellularly from the tymbal nerve while moths were subjected to selective severing of the suboesophageal, prothoracic, pterothoracic and abdominal ganglia connectives. Motor output evoked by either acoustic or tactile stimulation originates from a common CPG because tymbal nerve spikes in both cases are similar in amplitude, waveform and rhythmicity. Our results showed: (1) removal of the CNS posterior of the second abdominal neuromere had no effect, (2) removal of the head decreased the responsiveness of the animal to acoustic stimulation and, (3) severing the connectives between the prothoracic and pterothoracic ganglia abolished responses to acoustic stimuli and diminished responses to tactile stimuli. We conclude that although the minimal circuitry sufficient for activating the tymbals resides in the pterothoracic ganglion, the prothoracic and cephalic ganglia are required for the normal, and in particular, auditory-evoked operation of the tymbal CPG.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196419
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    A study of the K+-site mutant of ascorbate peroxidase: mutations of protein residues on the proximal side of the heme cause changes in iron ligation on the distal side (1999)
    Springer
    JBIC 4 (1999), S. 64-72 
    Details
    ISSN: 1432-1327
    Keywords: Key words Peroxidase ; Magnetic circular dichroism ; Ascorbate peroxidase ; Heme-containing enzyme ; Site-directed mutagenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract  A series of ferric and ferrous derivatives of wild-type ascorbate peroxidase (APX) and of an engineered K+-site mutant of APX that has had its potassium cation binding site removed have been examined by electronic absorption and magnetic circular dichroism (MCD) spectroscopy at 4  °C. Wild-type ferric APX has spectroscopic properties that are very similar to those of ferric cytochrome c peroxidase (CCP) and likely exists primarily as a five-coordinate high-spin heme ligated on the proximal side by a histidine at pH 7. There is also evidence for minority contributions from six-coordinate high- and low-spin species (histidine-water, histidine-hydroxide, and bis-histidine). The K+-site mutant of APX varies considerably in the electronic absorption and MCD spectra in both the ferric and ferrous states when compared with spectra of the wild-type APX. The electronic absorption and MCD spectra of the engineered K+-site APX mutant are essentially identical to those of cytochrome b 5, a known bis-imidazole (histidine) ligated heme system. It therefore appears that the K+-site mutant of APX has undergone a conformational change to yield a bis-histidine coordination structure in both the ferric and ferrous oxidation states at neutral pH. This conformational change is the result of mutagenesis of the protein to remove the K+-binding site which is located ∼8 Å from the peroxide binding pocket. Thus, mutations of protein residues on the proximal side of the heme cause changes in iron ligation on the distal side.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007750050290
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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