Transductional and structural principles of the mitochondrial transducing unit

The electromechanochemical model has been reformulated to take account of the close connection between energy coupling and catalysis. In catalysis the protein is programmed to utilize thermal energy to produce local strains in the catalytic cavity and to generate conformational states that favor substrate --> product conversion. Energy coupling involves transfer of vibrational energy through the protein. Underlying these two energy transductional maneuvers is the concept of a pulsating protein capable of redistributing electromechanochemical potential energy in a programmed fashion. The mitochondrial supermolecule has been defined, and it has been shown how the supermolecule concept rationalizes the coupling options, the stoichiometry of the coupling complexes, and the multistep character of electron transfer.

Electromechanochemical model of mitochondrial structure and function

A NEW MODEL OF MITOCHONDRIAL STRUCTURE AND FUNCTION IS PROPOSED ON THE BASIS OF FOUR FUNDAMENTAL ASSUMPTIONS: (a) electrons and protons are separated in the electron transfer complexes; (b) the ATPase undergoes conformational state-transitions induced by an electric field; (c) energy is transferred by an electric field effect; and (d) a conformationally strained protein system can be relaxed via a bond-forming chemical reaction. The model can explain all of the mitochondrial coupled processes and, in addition, it provides a reasonable rationalization of the correlation between mitochondrial structure and function.

Conformational model of active transport: role of protons

A conformational model of monovalent cation transport in mitochondria is described. Because it incorporates the proton-generated membrane potential and pH differential of the chemiosmotic model, the model successfully rationalizes a wide variety of mitochondrial ion-transport phenomena.

Conformational model of active transport

A model of active transport of monovalent cations in mitochondria is developed. The model is based on the coupling of electron transfer to the generation of a metastable protein conformation which in turn leads to the generation of an asymmetric surface charge, a membrane potential, and a redistribution of diffusible ions across the inner mitochondrial membrane. The ions at all times move spontaneously down an electrochemical potential gradient in this model so that there is no need to invoke the concept of an ion pump. It is shown that a wide variety of experimental facts can be rationalized in terms of the present model.

Biological membrane structure, I. The protein crystal model for membranes

A geometric model for the arrangement of phospholipid and protein in biological membrane systems has been proposed. The essential principle underlying this model is that when membrane proteins polymerize, the points of contact between proteins are few, and cavities lined with predominantly nonpolar amino acids are formed. Phospholipid molecules become oriented with the fatty chains inserted into the cavities while the polar heads remain on the surface of the membrane. This orientation applies to both faces of the membrane continuum. All the lipid known to be present in membranes can be accommodated in this manner. The body of evidence supporting this model has been presented.

Energized configurations of heart mitochondria in situ

Changes in the configurational state of the cristal membranes of rat heart mitochondria within the living cell can be induced by imposing energizing conditions. An exact correlation has been established between the configurational states of the cristal membrane and the energy states of the mitochondrion. The configurational changes observed in mitochondria in situ are comparable to those established for beef heart mitochondria in vitro and are consistent with the postulate of the conformational basis of energy transductions in membrane systems. The formation of paracrystalline arrays is one of the noteworthy features of configurational changes of mitochondria in situ.