Moore AL, Bonner WD. The effect of calcium on the respiratory responses of mung bean mitochondria.
BIOCHIMICA ET BIOPHYSICA ACTA 1977;
460:455-66. [PMID:
18169 DOI:
10.1016/0005-2728(77)90084-6]
[Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Purified mung bean hypocotyl mitochondria were examined for their capacity to carry out respiration-dependent accumulation of calcium. The addition of 0.1-1.0 mM calcium to mung bean mitochondria supplemented with succinate gave no stimulation of state 4 respiration even in the presence of inorganic phosphate and the ionophoretic antibiotic A-23187. Even at high calcium concentrations, no transient changes in the respiratory activity occurred and subsequent addition of ADP initiated a further state 3 response. Although the additions of calcium resulted in a rapid H+ ejection, it was insensitive to lanthanum and uncoupling agents. Similarly, additions of calcium failed to initiate any transient changes in the oxidation-reduction states of either pyridine nucleotides or cytochrome b. Direct spectrophotometric recordings of absorbance changes of murexide revealed no respiration-linked calcium transport. It is proposed that although mung bean mitochondria possess a respiration-linked electrochemical potential gradient it would appear that this potential cannot be expressed as calcium transport even at high ion concentrations, probably due to a low calcium membrane permeability.
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