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  • 1
    Electronic Resource
    Electronic Resource
    Ecophysiological studies on citrate synthase: (II) enzyme regulation of selected crustaceans with regard to life-style and the climatic zone (1995)
    Springer
    Journal of comparative physiology 165 (1995), S. 56-61 
    Details
    ISSN: 1432-136X
    Keywords: Citrate synthase ; Enzyme regulation ; Temperature adaptation ; ATP inhibition ; Crustacea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Citrate synthase is a regulatory enzyme of the energy metabolism pathway controlling the citric acid cycle. It was studied in order to determine modes of enzyme regulation with regard to the life-style of the investigated species. Citrate synthase from crustaceans with different life-styles were compared: the pelagic euphausiids Euphausia superba from the Antarctic and Meganyctiphanes norvegica from the Scandinavian Kattegat and the Mediterranean were compared to the benthic isopods Serolis polita from the Antarctic and Idotea baltica from the Baltic. Citrate synthase was partly purified chromatographically and the influence of adenosine 5′-triphosphate on enzyme activity was examined. Mechanisms of inhibition and inhibitor constants were determined. Two different mechanisms of enzyme regulation by ATP were found. Citrate synthase from isopods was only competitively inhibited, while citrate synthase from euphausiids showed not only competitive inhibition but also activation by low concentrations of ATP. This activation is equivalent to the reversed methanism of uncompetitive inhibition. The ecophysiological relevances of the coupling of these mechanisms are discussed. The degree of competitive inhibition was different in the two groups of investigated crustaceans. Inhibitor constants were similar within the euphausiids but not in isopods, which showed higher or lower inhibition depending on the climatic zone: the colder the ambient temperature the lower the ATP inhibition. A possible mechanism of temperature adaptation through effects of varying inhibition constants is concluded.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00264686
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Subband Modeling of the Human Cardiovascular System: New Insights into Cardiovascular Regulation (1998)
    Springer
    Annals of biomedical engineering 26 (1998), S. 293-307 
    Details
    ISSN: 1573-9686
    Keywords: Cardiovascular system ; Autonomic nervous system ; Subband decomposition ; Wavelet filter bank ; Multidimensional linear modeling ; Subband modeling ; Cardiovascular regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract We present a new approach to cardiovascular analysis based on a well-known signal processing technique, namely, the frequency subband decomposition. The subbands are chosen in accordance with physiological standards: (1) 0–0.04 Hz, (2) 0.04–0.15 Hz, (3) 0.15–0.4 Hz. It is shown that such a pre-processing drastically improves the accuracy of the analysis and introduces a new direction in the understanding of the relationships between cardiovascular signals. © 1998 Biomedical Engineering Society. PAC98: 8710+e
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1114/1.57
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    Paper (German National Licenses)
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