Theoretical study of an energy metabolizing system satisfying Mitchell's postulates.

An energy metabolizing system was modelled, which carries as characteristic features substrate uptake and product extrusion, respiration and ATP-synthesis, coupled by the protonmotive potential corresponding to Mitchell's chemiosmotic hypothesis of oxidative phosphorylation. The influence of the electric part of the protonmotive potential on the rate laws of the different processes has been taken into account by a phenomenological exponent of the proton concentration, thus fortifying the osmotic concentration part of the protonmotive potential. The steady-state behaviour of the model was investigated. It could be shown that a model of such kind reveals multistationarity, homeostasis and trigger behaviour. Curves of respiration control (respiration velocity over ADP/(ATP + ADP) or ATP/ADP) are in qualitative accordance with experimental facts (state 3 and state 4 of mitochondria) as well as curves describing the effect of uncouplers on the respiratory rate.