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The Effect of Cadmium on Electron and Energy Transfer Reactions in Corn Mitochondria
Author(s) -
MILLER R. J.,
BITTELL J. E.,
KOEPPE D. E.
Publication year - 1973
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.1399-3054.1973.tb01170.x
Subject(s) - cadmium , chemistry , phosphate , respiration , mitochondrion , biochemistry , biology , botany , organic chemistry
The effects of cadmium on isolated corn shoot mitochondria were determined. In the absence of phosphate cadmium stimulated the oxidation of exogenous NADH optimally at 0.025 m M , but was inhibitory at 0.1 m M and above. The presence of phosphate negated the cadmium stimulation of exogenous NADH oxidation and permitted inhibitions only at higher cadmium concentrations. Succinate or malate + pyruvate oxidation in the absence of phosphate was inhibited to a greater extent by cadmium than when phosphate was present. ADP/O and respiratory control ratios were reduced by cadmium but generally were less sensitive to cadmium than state 4 or minus phosphate respiration. The data suggest that the site of cadmium effect is likely to be early in electron transport. Cadmium had a pronounced effect on mitochondrial swelling under either passive or active conditions. When succinate or exogenous NADH were being oxidized swelling occurred at 0.05 m M cadmium, but with malate + pyruvate the cadmium concentration had to exceed 1.0 m M . Phosphate (2 m M ) prevented the swelling. Dithiothreitol, a SH group protector, prevented any effect of cadmium on swelling or respiration which suggests that sulfhydryl groups are likely involved in the cadmium‐membrane interaction.