Opposite modulation by uncoupling and electron transport limitation of the Kmapp of ADP for photophosphorylation

Vinkler, Chana

doi:10.1016/0006-291x(81)90731-2

Cited by 53 publications

(25 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Similar fluctuations were observed for c; in our oxidative phosphorylation experiments and could be gleaned from the results of others on chloroplast photophosphorylation. The latter data indicate that both KR"" and FA, as well as the rate of photophosphorylation, change as a direct function of the intensity of (or the duration of pulsed) illumination (Vinkler, 1981 ;Junge, 1987;Quick andMills, 1987, 1988). We have recently shown that venturicidin and tetracoordinate organotin compounds, which are potent mitochondria1 F,, inhibitors, do not cause complete inhibition, but only attenuate greatly the rate of energy flow between F, and F, (Matsuno-Yagi and Hatefi, 1993a, b).…”

Section: -160 11 000mentioning

confidence: 94%

See 1 more Smart Citation

ATP synthesis in mitochondria

Hatefi

1993

European Journal of Biochemistry

View full text Add to dashboard Cite

Section: -160 11 000mentioning

confidence: 94%

“…mol F,F,-') for the rate of chloroplast photophosphorylation (Vinkler, 1981 ;Junesch and Graber, 1985), which brings up an interesting point. We and others had long wondered why the rate of ATP synthesis/ mol ATP synthase was so much higher in photophosphorylation than in oxidative phosphorylation.…”

mentioning

confidence: 93%

ATP synthesis in mitochondria

Hatefi

1993

European Journal of Biochemistry

View full text Add to dashboard Cite

“…Previous studies with submitochondrial particles have given conflicting results, because whereas Schuster et al [I 81 found non-hyperbolic dependence of the rate of ATP synthesis on substrate concentration, Kayalar et al [3] reported linear double-reciprocal plots. In contrast rates of photophosphorylation by thylakoids have generally followed a hyperbolic relation to substrate concentration [4,19,201. There is also variation in the results of investigations of the kinetics of ATP hydrolysis by the purified F, sector of the ATP synthase, because many [21-261, but not all [I 51, studies revealed deviations from Michaelis-Menten kinetics.…”

Section: Discussionmentioning

confidence: 99%

“…Addition of 2,4-dinitrophenol to submitochondrial particles increased both S,,, (ADP) and S50% Pi [3]. With thylakoids conflicting results have been obtained, as Vinkler [4] found that several uncouplers raised Ssocx for ADP, whereas Strotmann and Bickel-Sandkotter (personal communication) found no change in Ssos., for either ADP or Pi upon adding ammonium ions as uncoupler. In addition Dewey and Hammes [5] reported insignificant changes in Ssoo; values when ApH was varied in asolectin phospholipid vesicles into which both bacteriorhodopsin and thylakoid ATP synthase had been incorporated.…”

mentioning

confidence: 99%

The Effects of Partial Uncoupling upon the Kinetics of ATP Synthesis by Vesicles from Paracoccus denitrificans and by Bovine Heart Sybmitochondrial Particles. Implications for the Mechanism of the Proton-Translocating ATP Synthase

McCarthy

Ferguson

1983

Eur J Biochem

View full text Add to dashboard Cite

) -EJB 6179 1. Reduction in the magnitude of the respiration-dependent protonmotive force (proton electrochemical gradient in mV) of vesicles from Paracoccus denitrificans, and of submitochondrial particles, has been found to be paralleled small increases in Ssoy;, values for both ADP and Pi. For example, reduction of the protonmotive force of P. denitrificuns vesicles from 145 mV to 110 mV was accompanied by an increase of Sstr;, (ADP) from 8 pM to l8pM, and an increase of Ssoui (Pi) from 0.33mM to 1.4mM. This result was obtained with partial uncoupling quantities of both carbonyl-cyanide p-trifluoromethoxyphenylhydrazone and of the synergistic combination of nigericin plus valinomycin in the presence of K'. In view of the similar effects of these two different methods of uncoupling it is concluded that the changes in S,o,:a were a consequence of the diminished protonmotive force acting on the ATP synthase rather than of a secondary, direct interaction of the uncouplers with the enzyme. Changes in Sso", rather than Ez, are described because under several sets of conditions double-reciprocal plots were nonlinear.2. For equivalent attenuations in the rate of ATP synthesis by submitochondrial particles, 2,4-dinitrophenol caused much larger increases in S,, : u (ATP) than did carbonylcyanide p-trifluoromethoxyphenylhydrazone. Therefore it is concluded that the effect of 2,4-dinitrophenol was primarily a consequence of its previously recognized direct interaction with the F, segment of the mitochondria1 ATPase. The concentration range of 2,4-dinitrophenol that raised Ssox (ADP) is similar to that which weakens the binding of ADP to a particular type of site on the purified F, sector of ATP synthase. This correlation is consistent with such a site having a catalytic role during ATP synthesis.3. A titration of the rate of ATP synthesis by vesicles of P. denitrificans with increasing quantities of carbonylcyanide p-trifluoromethoxyphenylhydrazone showed that the initial titres of the uncoupler caused large decreases in the rate of ATP synthesis for relatively small attenuations in the protonmotive force. Thus the initial 20 mV drop in the protonmotive force was accompanied by a reduction of more than 65% in the rate of ATP synthesis. Over the lowest range of values of protonmotive force that drove detectable rates of ATP synthesis however, the dependence of the rate was a less steep function of the protonmotive force. A plot of the logarithm of the rate of ATP synthesis against protonmotive force reveals a biphasic relationship. There does not appear to be a 'threshold' value of the protonmotive force below which ATP synthesis is blocked by kinetic factors.4. The relationships of the protonmotive force with Ssoyn values and with the rate of ATP synthesis (at near saturating concentrations of ADP and Pi) are discussed in relation to possible mechanisms for the coupling of proton translocation to ATP synthesis.Acceptance of the role of the protonmotive force as the intermediate between electron transport and ATP synthesi...

show abstract

“…Our proposal in the previous paragraphs shows how this coupling could occur. Conformational changes in chloroplast and mitochondria1 H+-ATPases in response to membrane energization are well documented [46 -5 I] as are changes in the K , and sulfhydryl group reactivity of the ATPases upon energization [52,53]. The catalytic activity of the heat-activated or light-activated ATPase is inhibited by MalNEt,indicatingthat conformational changes occur during the activation in which sulfhydryl groups become available (54-561, Farron and Racker [55] proposed that the conformational change which occurred upon heat activation proceeded via sulfhydryl-disulfide interchange.…”

Section: Energy Transduction and Proton Pumpingmentioning

confidence: 99%

A Hypothesis for the Role of Dithiol‐Disulfide Interchange in Solute Transport and Energy‐Transducing Processes

Robillard

Konings²

1982

European Journal of Biochemistry

139

View full text Add to dashboard Cite

We have recently shown that the physical mechanism for A,GH+-driven changes in the K, for three different transport systems is an oxidation-reduction reaction involving a dithiol-disulfide interconversion [Robillard, G. T. and Konings, W. N. (1981) Biochemistry, 20, 5025-5032;Konings, W. N. and Robillard, G. T. (1982) Proc. Nut1 Acad. Sci. U S A , in the press]. Based on the similarities between the data from these three systems and published data from other systems, we now propose that dithiol-disulfide interchange may play a general role in membranerelated processes such as transport, energy transduction and hormone-receptor interactions.We propose that the affinities of the substrate-binding sites are regulated by a dithiol and a disulfide situated at different depths in the membrane. In addition we propose that the oxidation states of these two redox centers are coupled by dithiol-disulfide interchange such that. when one is oxidized, the other is reduced. Since a transmembrane electrical potential, A $ , or a pH gradient, ApH, can alter the redox state, it can change the affinity of the substratebinding sites. The Afii,+-induced changes in affinity are sufficient to drive active transport (symport or antiport) and energy-transducing processes. A similar mechanism can be applied to transport systems driven by phosphorylated enzyme intermediates instead of A f i H + .Changes of the redox potential in a given compartment during metabolism could also control the affinity of ligand binding even in the absence of a A , i i~+ .The ligand-binding affinities of facilitated diffusion transport systems and receptor proteins may be regulated in this manner.

show abstract

Opposite modulation by uncoupling and electron transport limitation of the Kmapp of ADP for photophosphorylation

Cited by 53 publications

References 14 publications

ATP synthesis in mitochondria

ATP synthesis in mitochondria

The Effects of Partial Uncoupling upon the Kinetics of ATP Synthesis by Vesicles from Paracoccus denitrificans and by Bovine Heart Sybmitochondrial Particles. Implications for the Mechanism of the Proton-Translocating ATP Synthase

A Hypothesis for the Role of Dithiol‐Disulfide Interchange in Solute Transport and Energy‐Transducing Processes

Contact Info

Product

Resources

About