ISSN:
1432-2048
Keywords:
Mitochondria
;
NADH oxidation
;
Respiration (rotenone-resistant)
;
Temperature activation
;
Vicia
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract 1. Respiration rates of broad-bean (Vicia faba) mitochondria were studied as a function of temperature. Arrhenius plots of all membrane-bound enzymes, as obtained with saturating substrate concentrations, revealed a break in the lower temperature range. That break was considered to indicate a phase transition of membrane phospholipids, characteristic for chilling-sensitive plants. A second discontinuity at 30°C occurred only with activities linked to energy conservation. — 2. The activation energies for the oxidation of NAD+-linked substrates differ between states 3 and 4. State 3 respiration of NAD+-linked substrates is the result a superimposition of two branches of electron transport, which can be separated by different sensibilities to rotenone. A characteristic temperature dependency of the respiratory control, as well as a shift of the low temperature break in the Arrhenius plot toward a higher temperature after state 4 to state 3 transition, are calculated to be caused by the superimposition of the two branches. — 3. The temperature dependency of the oxidation of extra-mitochondrial NADH and of succinate differs remarkably from that of the oxidation of matrix-NADH. It has been concluded that the rotenone-resistant oxidation of matrix-NADH and the oxidation of external NADH are mediated via different pathways with individual regulation sites.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00391579
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