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Calmodulin is not involved in the regulation of exogenous NADH oxidation by plant mitochondria
Author(s) -
Schwitzguébel JeanPaul,
Nguyen Tan Duc,
Siegenthaler PaulAndré
Publication year - 1985
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.1399-3054.1985.tb01901.x
Subject(s) - calmodulin , mitochondrion , egta , biochemistry , chemistry , cytochrome c , electron transport chain , enzyme , nadh dehydrogenase , biology , calcium , protein subunit , organic chemistry , gene
The oxidation of exogenous NADH by mitochondria from potato ( Solanum tuberosum L., cv. Bintje) tubers, measured with different electron acceptors, oxygen, cytochrome c , duroquinone and ubiquinone 1, was greatly enhanced under high salt conditions compared to low salt conditions, confirming the stimulatory effect of electrostatic screeening of negative membrane charges by cations. In addition to this nonspecific stimulation, the oxidation of exogenous NADH showed a specific dependence on Ca 2+ . Results presented here suggest that calmodulin was not directly involved in the regulation of exogenous NADH oxidation by potato mitochondria: (1) Calmodulin antagonists were found to inhibit electron flow at several sites in a nonspecific manner. (2) Using a phenothiazine‐Affi Gel column, it was not possible to demonstrate the presence of calmodulin in Triton X‐100 solubilized mitochondria. (3) Fractions eluted from a calmodulin‐Sepharose column with EGTA [ethyleneglycolbis (β‐aminoethylether)‐N, N, N′, N′‐tetraacetic acid] did not display any activity related to mitochondrial electron transport, suggesting that NADH dehydrogenase had no specific affinity for calmodulin. The possible indirect involvement of calmodulin in the regulation of exogenous NADH oxidation by Ca 2+ is discussed.