ISSN:
1432-136X
Schlagwort(e):
Citrate synthase
;
Enzyme characteristics
;
Temperature adaptation
;
Isopod crustacea
;
Euphausiid crustacea
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Biologie
,
Medizin
Notizen:
Abstract The characteristics and properties chromatographically purified citrate synthase from the euphausiids Euphausia superba (Antarctica) and Meganyctiphanes norvegica (Scandinavian Kattegat and Mediterranean Sea) and from the isopods Serolis polita (Antarctica) and Idotea baltica (Baltic Sea) were used to elucidate biochemical mechanisms of temperature adaptation. Additionally, maintenance experiments were carried out on the euphausiids to determine mechanisms of short term acclimation. Temperature optima (between 37 and 45°C) were unrelated to genotypic cold adaptation, but the activation energy of the Antarctic krill E. superba (10.9 kJ · mol-1) was only a quarter of that in other species (41.8–45.1 kJ · mol-1). The minima of apparent Michaelis constants (total range: 4–20 μmol · 1-1 oxaloacetate; 7–45 μmol · 1-1 acetyl-coenzyme A) showed no relation to natural conditions, and no distinct pH optimum occurred at ambient temperatures. In contrast, apparent Michaelis constants and specific enzyme activities were related to maintenance temperatures in M. norvegica, but not in E. superba. The differences between M. norvegica and E. superba can be interpreted as adaptations to the changes in ambient temperature with regard to the respective steno- and eurythermic tolerances of these crustaceans.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00264685
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