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THE MODEL SYSTEM: PREPARATION AND CHARACTERIZATION OF BACTERIAL MEMBRANE VESICLES H.R. Kaback

THE MODEL SYSTEM: PREPARATION AND CHARACTERIZATION OF BACTERIAL MEMBRANE VESICLES H.R. Kaback.

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THE MODEL SYSTEM: PREPARATION AND CHARACTERIZATION OF BACTERIAL MEMBRANE VESICLES H.R. Kaback

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  1. THE MODEL SYSTEM: PREPARATION AND CHARACTERIZATION OF BACTERIAL MEMBRANE VESICLESH.R. Kaback

  2. D-lactate is converted to pyruvate by a peripherally bound, flavin-linked D-lactate dehydrogenase. The bacterial plasma membrane, like the mitochondrial inner membrane, contains a respiratory chain, and anoxia or various inhibitors of electron transfer block both the conversion of D-lactate to pyruvate and active transport. Thus, oxidation of D-lactate to pyruvate by D-lactate dehydrogenase is coupled to a membrane-embedded respiratory chain, and as will be shown subsequently, electron transfer leads to the generation of a proton electrochemical gradient that is used to perform work in the form of active transport.

  3. Figure 11. Each membrane vesicle catalyzes active transport.

  4. The preparation and characterization of bacterial membrane vesicles as a model system in which to study active transport led to the development of similar cytoplasmic membrane vesicle systems from eucaryotic cells, intestinal and kidney epithelia, as well as vesicles from intracellular organelles such as chromaffin granules, synaptosomes, etc. However, since these membranes do not contain a respiratory chain, artificially imposed ion gradients or ATP are used to drive active transport.

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