| Autor: |
Reizer, Jonathan, Epstein, Israel, Grossowicz, Nathan |
| Předmět: |
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| Zdroj: |
European Journal of Biochemistry; 8/1/77, Vol. 77 Issue 3, p463-470, 8p |
| Abstrakt: |
The effect of growth temperature on activity and rate of synthesis of the α-aminoisobutyric acid transport system and of several enzymes of Bacillus stearothermophilus var. non diastaticus was investigated. The uptake of α-aminoisobutyrate, as well as the activities of alanine dehydrogenase and aliphatic amidase were found to be considerably reduced in cultures grown at the near maximal temperature for growth (65 °C) as compared to those grown at the optimal temperature for growth (58 °C), although the growth rates at both temperatures were similar. The reduced rate at 65 °C was due to a decreased differential rate of synthesis of these activities, while the increase in the activities at 58 °C was due to de novo synthesis of the enzymes and the α-aminoisobutyrate transport system rather than to activation of pre-existing inactive enzymes or permeases. The highest rate of synthesis of alanine dehydrogenase and of the α-aminoisobutyrate-uptake system was obtained in cells grown at the near minimal temperature for growth (42-45 °C). The reduced rate of enzyme synthesis at the higher temperatures seemed to be due both to an increase in catabolite repression and to faulty oxidative metabolism during growth at these temperatures. The effects mentioned were only partly abolished in a mutant resistant to catabolite repression, when grown at the high temperatures. The thermoadaptation process is discussed in terms of energy production and ATP availability for protein biosynthesis. The alterations of the metabolic activities induced by the environmental temperature were reversible and represent a physiological thermoadaptative response of the cells. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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