Moving Questions: A History of Membrane Transport and Bioenergetics (People and Ideas)

This book describes a half century of research on cellular membrane transport and on metabolic energy capture and utilization. During this time-which begins in the late 1930s-the effort and imagination of various scientists overthrew reigning formulations, created novel explanatory models, and unified previously distinct experimental fields. My primary goal is to display the course of that research, showing how new experiments defined novel entities and processes, and how an encompassing field, bioenergetics, then emerged. A secondary goal is to present examples of mainstream biological research that illustrate how experimental results-seen as refutations, confirmations, and elabora­ tions-can sway opinion toward a solid consensus. This interpretation differs from the currently fashionable view of some commentators that stresses instead the central roles of power, prestige, gender, class, and ethnicity. In any case, the scien­ tific practices exhibited here deserve proper philosophical scrutiny. Although con­ straints of space have squeezed any analysis from this draft, brief mention of salient issues does appear in relevant chapters and in the final conclusions. (Oddly, histori­ ans and philosophers seem reluctant to deal with this science. Those who do consider biological topics tend to focus on the theory of evolution, even though the bulk of biological research in this century, in terms of papers published and technology influenced, has dealt not with evolution per se but with what may be termed physiology and biochemistry. And these endeavors, which are the aims, efforts, and accomplishments of the vast majority of biologists, have been largely ignored. This book describes half a century of progress in two mainstream areas of biological research: membrane transport, initially a focus of physiologists, and oxidative phosphorylation, initially a focus of biochemists. Robinson shows how the development of new explanatory models had unexpectedly merged these inquiries into a new field, bioenergetics. In the late 1930s, explanations for the asymmetric distribution of ions between cells and their environments invoked absolute impermeabilities of the cell's surrounding membranes. But new experiments contradicted that idea and demonstrated that forming the transmembrane distributions required metabolic energy, implying the participation of active transport "pumps." Subsequent studies identified, isolated, and characterized these pumps as enzymes coupling ionic transport to the consumption of adenosine triphosphate (ATP), an "energy-rich" molecule serving as a cellular energy store. In the late 1930s oxidative phosphylation, the process of coupling ATP synthesis to oxidative metabolism, was identified. The explanatory model emerging in the next decades, however, did not follow the enzymatic precedents of known metabolic phosphorylations but rather embodied the principle that metabolic oxidations drive active transport pumps to create transmembrane distribution of ions, with these ionic asymmetries then driving ATP synthesis. It was discovered that ATP consumption can form ionic asymmetries; ionic asymmetries can drive ATP formation; and ionic asymmetries-like ATP-can also power other cellular functions This book describes half a century of progress in two mainstream areas of biological research: membrane transport, initially a focus of physiologists, and oxidative phosphorylation, initially a focus of biochemists.Robinson shows how the development of new explanatory models, and unexpectedly merged these inquiries into a new field, bioenergetics. In the late 1930s, explanations for the asymmetric distribution of ions between cells and their environments invoked absolute impermeabilities of the cell's surrounding membranes. But new experiments contradicted that idea and demonstrated that forming the transmembrane distributions required metabolic energy, implying the participation of active transport "pumps." Subsequent studies identified, isolated, and characterized these pumps as enzymes coupling ionic transport to the consumption of adenosine triphosphate(ATP), an "energy-rich" molecule serving as a cellular energy store. In the late 1930s oxidative phosphylation, the process of coupling ATP synthesis to oxidative metabolism, was identified. The explanatory model emerging in the next decades, however, did not follow the enzymatic precedents of known metabolic phosphorylations but rather embodied the principle that metabolic oxidations drive active transport pumps to create transmembrane distribution of ions, with these ionic asymmetries then driving ATP synthesis. ATP consumption can form ionic asymmetries; ionicasymmetries can drive ATP formation. And ionic asymmetries-like ATP-can also power other cellular functions. Front Matter....Pages i-1 Introduction....Pages 3-12 Views in the 1930s....Pages 13-25 Accounting for Asymmetric Distributions of Na + and K + in Muscle....Pages 26-52 Accounting for Asymmetric Distributions of Na + and K + in Red Blood Cells....Pages 53-67 Ion Gradients and Movements in Excitable Tissues....Pages 68-88 Epithelial Transport by Frog Skin....Pages 89-97 Contemporary Events: 1939–1952....Pages 98-102 Characterizing the Na + /K + Pump....Pages 103-125 Identifying the Na + /K + -ATPase....Pages 126-146 Contemporary Events: 1953–1965....Pages 147-155 Characterizing the Na + /K + -ATPase....Pages 156-182 Structure and Relatives of the Na + /K + -ATPase....Pages 183-204 Alternatives....Pages 205-219 Using the Transmembrane Cation Gradients: Transporters and Channels....Pages 220-237 Contemporary Events: 1966–1985....Pages 238-246 Oxidative Phosphorylation: Chemical-Coupling Hypothesis....Pages 247-260 Oxidative Phosphorylation: Chemiosmotic Coupling Hypothesis....Pages 261-282 Oxidative Phosphorylation: F 1 , F 0 F 1 , and ATP Synthase....Pages 283-299 Conclusions....Pages 300-311 Back Matter....Pages 312-373