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Succinate oxidation by coupled potato tuber mitochondria followed by rapid scan spectrometry
Author(s) -
DUCET GASTON
Publication year - 1980
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1980.tb04457.x
Subject(s) - redox , cytochrome , membrane , mitochondrion , cytochrome c , chemistry , oxidation state , biochemistry , enzyme , organic chemistry , catalysis
Oxidation of succinate by potato tuber mitochondria has been investigated from aerobiosis to complete anuerobiosis. Difference spectra of the various steps were recorded by a rapid scan spectrometer delivering averaged spectra every 3 s in the range 380 to 630 mm. The transitions between state 3 and 4 resulted in large redox changes, essentially for the b cytochromes, and in significant changes in the spectral baseline (light scattering). At anaerobiosis the cytochromes c, c 1 and a were reduced while cytochrome a , remained oxidized. – Addition of uncouplers in aerobiosis induced oxidation of the b cytochromes, and when anaerobiosis occurred cytochromes c, c 1 a and a 3 were reduced simultaneously. When uncouplers were added in anaerobiosis a partial oxidation of the b cytochromes and the reduction of cytochrome a 3 were observed. These results are interpreted as the building up of a membrane potential, maximal in state 4 and stable after anaerobiosis. The cytochromes buried in the membrane equilibrate with the membrane potential, and their redox states are sensitive to the changes. Variations of membrane potential also induce changes in the light scattering by the mitochondrial membrane.