Microwave Hall mobility measurements on heavy beef heart mitochondria

The observed initial microwave Hall mobility values at 1·21 tesla of heavy beef heart mitochondria is at least six times greater than that observed for bovine serum albumin at similar resistivity values. The respiratory inhibitor cyanide significantly reduces the initial Hall mobility values for HBHM and for a preparation of HBHM cytochrome oxidase.The four enzymic complexes of the respiratory chain were partially or completely separated. Of these complexes cytochrome oxidase exhibits the largest microwave Hall mobility.The maximum hydration content of loosely bound water for freezedried preparations of cytochrome oxidase is 5% by weight; 60% of this hydration content is driven off by microwave power. Since the effective ac resistivity of the samples of cytochrome oxidase did not appreciably vary with changes in hydration content, the true resistivity of cytochrome oxidase has a value of the order 5×10³ ohm cm and possibly much lower.The electron transport pathway (as measured by Hall signal) of cytochrome oxidase is irreversibly damaged by prolonged exposure to microwave irradiation at 9·2 GHz. This is accompanied by the complete loss of capacity to oxidise ferrocytochromec. Such changes do not occur with HBHM or with the other respiratory complexes.There appears to be a direct relationship between observed Hall signals and the capacity of cytochrome oxidase to oxidize ferrocytochromec. There is a background signal which is not directly related to electron transport but which is dependent on the conformation of the cytochrome oxidase.The observed electronic parameters of cytochrome oxidase do not depend appreciably on its redox state.Acid denaturation of cytochrome oxidase drastically reduces the Hall signal, to include almost complete removal of the background signal. It also more than doubles ac resistivity.An electron tunnelling model is outlined.