Abstract
Hepatic microsomal electron transport system is one of unique models for studying membrane-bound multi-enzyme systems, as the electron transfer between the components involves direct protein-protein interaction in the membrane. Although the determination of the interaction mode between them has been the aim of many studies, no conclusive evidence has been obtained.
To elucidate this mechanism, the isolated protein components were incorporated into artificial model membranes and electron transfer was measured directly by stoppedflow techniques. The results obtained indicate the lateral mobility of these protein components in the membrane and the effect of fluidity changes in the membrane suggests that electron transfer between them is a diffusion-limited process.
On the contrary, several lines of evidence in favor of heterogeneous distribution of these components in the microsomal membranes has been reported. A mechanism which can explain the discrepancy between model systems and the microsomal system is discussed.
