Differential effects of mercurial reagents on membrane thiols and on the permeability of the heart mitochondrion

Cited by 85 publications

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“…Any manipulation which removed the mitochondria from substrate (NADH), produced anoxia or reduced external As concentrations resulted in rapid As efflux, vitiating results. Mersalyl did not block the loss, and concentrations above 20 to 25 ,uM seemed to enhance leakage in some preparations, probably due to the enhanced permeability mercurials can produce (18). The only technique which would give reproducible results was rapid filtration without any washing.…”

Section: Resultsmentioning

confidence: 95%

Functioning of the Adenine Nucleotide Transporter in the Arsenate Uncoupling of Corn Mitochondria

Bertagnolli¹,

Hanson²

1973

Plant Physiol.

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Arsenate uncouples mitochondrial respiration in a process stimulated by ADP, inhibited by oligomycin, and competitively inhibited by inorganic phosphate. If mersalyl is added to corn mitochondria to block further transport of accumulated arsenate, the uncoupled respiration continues unabated due to recycling of matrix arsenate. Addition of ADP now inhibits rather than promotes respiration and the mitochondria shrink. It is established by arsenate analyses that arsenate is removed from the matrix. Oligomycin or atractyloside block the removal by inhibiting ADP-arsenate formation or transport, respectively. It is deduced that ADP-arsenate is stable in the membrane and is transported outward for hydrolysis in the external aqueous phase. Hence, ADP-arsenate formed in oxidative phosphorylation is not directly released to the matrix, and a mechanism must exist for its direct transfer to the transporter.The findings that arsenate uncoupling of mitochondrial respiration is oligomycin-sensitive (4,7,8,14,15), [6][7][8][9]15,21), and competitively inhibited by [5][6][7][8]21) has led to the opinion that instability of the ADP-As' bond formed in oxidative phosphorylation is responsible (7). It appears implicit in this view that the Fr7ATPase forms the arsenylated analog of ATP which is hydrolyzed either in the membrane or on release to the matrix, recycling As and ADP as acceptor. However, Ernster et al. (7) We report here on further studies of this phenomenon. The initial supposition is supported. The ADP-stimulation of arsenate uncoupling involves the AdN transporter, and it appears that oxidative phosphorylation-or arsenylation in this caseis accomplished without direct flux of adenine nucleotides in and out of the matrix. MATERIALS AND METHODSMitochondria. Corn mitochondria (Zea mays L. WF9(Tms)-xM14) were isolated, and recordings of oxygen consumption and percentage transmission were as previously described (10). Final suspension of the mitochondria (10-15 mg protein/ml) was in the same medium as used for the basic reaction mixture: 200 mm sucrose, 10 mm TES buffer, 1 mm MgSO, and 1 mg/ml bovine serum albumin, adjusted to pH 7.6 with KOH. Including a correction for the bovine serum albumin of the basic reaction mixture, protein concentrations were determined by the method of Lowry et al. (16). All preparations of mitochondria were checked for tight coupling by determining respiratory control and ADP/O ratios. Arsenate Transport. Radioactive 7"As (Amersham/Searle as arsenic acid in 0.04 M HCl) was mixed with potassium arsenate stock as carrier. For each experiment, a 0.1-ml aliquot of mitochondrial suspension was added to 0.9 ml of basic reaction mixture (28-29 C) with aeration by stirring. After additions (Table II), 100-1l aliquots (about 0.15 mg of protein) were withdrawn, and the mitochondria were collected on 0.45-,um pore size Millipore filters with suction being applied for 15 sec. The filters were dried, toluene based scintillation fluid (toluene-PPO-POPOP) was added, and the vials were counted.Atracty...

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Section: Resultsmentioning

confidence: 95%

Functioning of the Adenine Nucleotide Transporter in the Arsenate Uncoupling of Corn Mitochondria

Bertagnolli¹,

Hanson²

1973

Plant Physiol.

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“…A hypothesis was put forward [9,10] that endogenous mitochondrial ionophores for monovalent and divalent cations described [ 1 l-l 31, normally latent in isolated mitochondria, are unmasked by mercurials. On the other hand, permeability changes induced by mercurials in the inner mitochondrial membrane have been shown [7,14] to depend on the amount of thiol groups blocked and the extent of penetration of the mercurial into the membrane. This suggests that a distortion produced by the agent in the membrane proteins rather than mobilization of latent ionophores may be responsible for the increased permeability.…”

Section: Introductionmentioning

confidence: 99%

On the mechanism of mercurial‐induced permeability of the mitochondrial membrane to K⁺

Bogucka

Wojtczak

1979

FEBS Letters

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“…conditions, but which blocks the mitochondrial phosphate transporter system (25)(26)(27). This result suggests that the accumulation of Pi is essential, for the change in morphology.…”

Section: Resultsmentioning

confidence: 94%

On the "Energized-Twisted" Configuration of Isolated Beef Heart Mitochondria

Hunter

Brierley

1971

The Journal of Cell Biology

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Differential effects of mercurial reagents on membrane thiols and on the permeability of the heart mitochondrion

Cited by 85 publications

References 26 publications

Functioning of the Adenine Nucleotide Transporter in the Arsenate Uncoupling of Corn Mitochondria

Functioning of the Adenine Nucleotide Transporter in the Arsenate Uncoupling of Corn Mitochondria

On the mechanism of mercurial‐induced permeability of the mitochondrial membrane to K⁺

On the "Energized-Twisted" Configuration of Isolated Beef Heart Mitochondria

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Differential effects of mercurial reagents on membrane thiols and on the permeability of the heart mitochondrion

Cited by 85 publications

References 26 publications

Functioning of the Adenine Nucleotide Transporter in the Arsenate Uncoupling of Corn Mitochondria

Functioning of the Adenine Nucleotide Transporter in the Arsenate Uncoupling of Corn Mitochondria

On the mechanism of mercurial‐induced permeability of the mitochondrial membrane to K+

On the "Energized-Twisted" Configuration of Isolated Beef Heart Mitochondria

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On the mechanism of mercurial‐induced permeability of the mitochondrial membrane to K⁺