Respiration in non-phosphorylating yeast mitochondria. Roles of non-ohmic proton conductance and intrinsic uncoupling.
Respiratory rate, protonmotive force and charge/O ratio were measured under two different kinds of steady state in non-phosphorylating yeast mitochondria: (i) when the electron flux was modulated by a variable limitation in electron supply or (ii) when oxygen consumption was decreased by respiratory chain inhibitor titration. We showed that the relationships between either delta p or charge/O ratio and respiratory rate are different under the two kinds of steady state, indicating different degrees of intrinsic uncoupling in respiratory chain. Moreover, we observed a non-ohmic dependence between H(+)-conductance and delta p. We concluded that the high rate of static-head respiration in yeast mitochondria was determined both by the non-ohmic proton conductance of the inner membrane and the saturation of the redox proton pump slipping.
Ouhabi
R
R
Institut de Biochimie Cellulaire et Neurochimie du CNRS, Université de Bordeaux II, France.
Rigoulet
M
M
Lavie
J L
JL
Guérin
B
B
D004553:Electric Conductivity; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008928:Mitochondria / Q000378:metabolism*; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D010766:Phosphorylation; D011188:Potassium / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism* / Q000648:ultrastructure
D011188:Potassium