1. Further thermal characterization of an aspartate aminotransferase from a halophilic organism
- Author
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M C Alvarez-Ossorio, Francisco J. G. Muriana, and Angel M. Relimpio
- Subjects
chemistry.chemical_classification ,Halobacteriales ,Halobacteriaceae ,Calorimetry, Differential Scanning ,biology ,Aspartate transaminase ,Cell Biology ,biology.organism_classification ,Biochemistry ,Halophile ,Transaminase ,Enzyme Activation ,Haloferax mediterranei ,Enzyme ,chemistry ,Enzyme Stability ,biology.protein ,Thermodynamics ,Thermal stability ,Aspartate Aminotransferases ,Molecular Biology ,Research Article - Abstract
Aspartate aminotransferase (AspAT, EC 2.6.1.1) from the halophilic archaebacterium Haloferax mediterranei was purified [Muriana, Alvarez-Ossorio and Relimpio (1991) Biochem. J. 278, 149-154] and further characterization of the effects of temperature on the activity and stability of the halophilic AspAT were carried out. The halophilic transaminase is most active at 65 degrees C and stable at high temperatures, under physiological or nearly physiological conditions (3.5 M KCl, pH 7.8). Thermal inactivation (60-85 degrees C) of the halophilic AspAT followed first-order kinetics, 2-oxoglutarate causing a shift of the thermal inactivation curves to higher temperatures. The salt concentration affected the thermal stability of the halophilic transaminase at 60 degrees C, suggesting that disruption of hydrophobic interactions may play an important role in the decreased thermal stability of the enzyme.
- Published
- 1994
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