The objective of the proposed study is to determine the characteristics and role of diffusion of membrane components which catalyze mitochondrial electron transport and ATP synthesis. The ultimate goal is to determine whether maximal electron transport is diffusion controlled in addition to diffusion coupled and as opposed to reaction controlled. Toward this end we will study three different levels of organization, the intact mitochondrion (most complex), the intact inner membrane or mitoplast (intermediate level), and the engineered or reconstituted membrane (least complex). Specific studies will include: (i) the characteristics of cytochrome c diffusion in the intact mitochondrion and on the mitoplast membranes; (ii) the diffusion of FoF1 ATPase and ADP/ATP exchange protein in the intact mitochondrion, mitoplast and engineered, reconstituted membranes; (iii) the rates of lateral diffusion of redox components related to electron transfer in the mitoplast membrane and reconstituted membranes; and (iv) the proximity relationships between inner membrane Complexes in functional reconstituted membranes. To resolve the relationship between diffusion and electron transport in these different membrane types, we will vary well defined physical and chemical parameters such as membrane energization, matrix density, ionic strength, pH, specific ions, redox component concentration, membrane viscosity and tempertature, while monitoring the effects of these variables on diffusion and electron transfer rates. Based on data generated in this way, we will be able to determine whether there is a dependency of electron transport on independent diffusion of redox components consistent with two dimensional diffusion theory, the hydrodynamic theory of slow viscous flow and the theory of rate processes. These studies generally will test the validity of the "random collision model" of electron transport and will generate considerable fundamental new information regarding the mitochondrial energy conserving, life supporting process.
NIH ExPorter
NIH ExPorter