has been used to quantify the amount of control exerted by different steps on mitochondrial oxidative phosphorylation in rat-liver mitochondria. Inhibitors were used to manipulate the amount of active enzyme. The control strength of the adenine nucleotide translocator was measured by carrying out titrations with carboxyatractyloside.In state 4, the control strength of the translocator was found to be zero. As the rate of respiration was increased by adding hexokinase, the control strength of the translocator increased to a maximum value of -30% at -80% of state 3 respiration. In state 3, control of respiration is distributed between a number of steps, including the adenine nucleotide translocator, the dicarboxylate carrier and cytochrome c oxidase. The measured values for the distribution of control agree very well with those calculated with the aid of a model for mitochondrial oxidative phosphorylation developed by
The mechanism by which non-esterified long-chain fatty acids (FFA) promote mitochondrial permeability transition (MPT) is not clear. We examined with energized rat liver mitochondria the role of two possible actions of FFA in MPT, (i) the reduction of the transmembrane potential (v vi i) and (ii) the increase of the negative surface charge of the inner mitochondrial membrane [Broekemeier, K.M. and Pfeiffer, D.G., Biochemistry 43, (1995) 16440^16449]. It was found that the ability of FFA to stimulate large amplitude swelling is clearly related to their uncoupling activity. Moreover, compared with classical protonophores (FCCP) FFA increase the sensitivity of the pore opening process to v vi i changes. In addition, FFA interact like their thioester derivatives in a structure-dependent manner with the ADP/ATP carrier (measured as inhibition of [ Q H]atractyloside binding to the AAC protein). It is suggested that not only the protonophoric action of FFA, but also a presumable stabilization of the`cytosolic' conformation of AAC contribute to the FFA-promoted MPT.z 1997 Federation of European Biochemical Societies.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.