Bioenergetics of Halobacterium Halobium and of H. Marismortui
Changes in ATP have been followed in vivo by P-NMR. Uncouplers (protonophores and ionophores), were shown to inhibit ATP synthesis, growth and respiration, but had little or no effect on pH gradients either in H. halobium or in H. marismortui. The K gradient, which was dissipated in H. halobium when uncouplers were used at 10 times the concentrations that inhibited metabolic reactions, remained intact in H. marismortui with uncouplers at 1000 times these concentrations. The electrical conductance of the membranes of H. marismortui was found to be 2000 s/cm2, one million times larger than that of H. halobium. These observations are not consistent with the chemiosmotic paradigm. It is suggested that enhanced interactions of water molecules are involved in maintaining large ionic gradients. Evidence for the existence of an enhancement of this sort comes from NMR, calorimetric and dielectric measurements.
H. halobium and H. marismortui belong to the Archaeobacteriaceae and thus are low in the evolutionary hierarchy. In other words, they are primitive organisms. The H. marismortui membranes possess unusual features and a question arose as to whether the biochemical and physiological mechanisms of this organism are more primitive than those of more advanced organisms.
When anaerobic preparations of H. marismortui supplied with glycerol and oxygen were examined in vivo by P-NMR, ATP was found to be synthesized at a reasonable rate [1,2]. It should be pointed out that the methods used to measure ATP marismortui. These gradients could bring about a localised conduction of the ions through the ATP synthetase system and thus ATP synthesis.
KeywordsHalophilic Bacterium Cell Water Dielectric Dispersion Localise Conduction Halophilic Microorganism
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