Molecular Aspects of Bioelectricity (eBook)

Eberhard Neumann, Ernest Schoffeniels (Herausgeber)

eBook Download: PDF | EPUB

2014 | 1. Auflage
362 Seiten
Elsevier Science (Verlag)
978-1-4831-8985-7 (ISBN)

Infos

Molecular Aspects of Bioelectricity describes the self-organization in molecular and cellular networks. This book evaluates the chemical representation of ion flux gating in excitable biomembranes and addresses the theoretical implication of liganding reactions in axonal sodium channel gating. It also strongly demonstrates the ligand interactions of crustacean axonal membrane. The opening chapters deal with the biochemical studies of the structure, mechanism, and differentiation of the voltage-sensitive sodium channel; and biochemical cycle of impedance variation in axonal membranes. The succeeding chapters examine the effect of various compounds on the phosphorylation of nerve proteins and the molecular aspects of the actions of cyclic nucleotides at synapses. These topics are followed by discussions of the acetylcholine and choline acetyltransferase, as well as the polymorphism of cholinesterase in vertebrates. The closing chapters are devoted to the physical factors determining gated flux from and into sealed membrane fragments. The book can provide useful information to biologists, students, and researchers.

Textauszug

OPENING ADDRESS

E. Schoffeniels,     Laboratory of general and comparative Biochemistry, University of Liège, 17, place Delcour, B 4020 Liège, Belgium

It is my great pleasure indeed to welcome you in Liège to participate at this symposium on molecular aspects of bioelectricity. I must confess that when the organizers started to plan this meeting they did not realize that it would coincide with the Thousandth anniversary of the Principalty of Liège and also with the 150th anniversary of Belgium. This obviously add to our pleasure to have been able to gather such a distinguished company of scientists in our City.

As we have already announced the main topics of this symposium cover a research field that has been initiated and profoundly shaped by the pioneering work of David Nachmansohn. More than forty years ago, David Nachmansohn made the proposition that it is rather illusory to try to understand bioelectricity if one neglects to consider it as a mere epiphenomenon of a more complex biochemical cycle.

As early as 1937, Nachmansohn proposed that acetylcholine in conjunction with adequate enzymes could be the specific operating substance that controls the generation of bioelectricity.

Tirelessly since that time, David Nachmansohn has always emphasized the fact that complex biochemical processes underly the profound restructuration occurring within the conducting membrane and a decisive step was achieved when, in the early Fifties, David Nachmansohn attributed the permeability changes leading to action currents to a transconformation of a specific protein.

This idea, rather novel when considered in the light of the paradigms prevailing among the scientists of the time was proven to be correct.

Since most of the lectures or posters will allude to Nachmansohn’s idea I shall not attempt to survey them in an exhaustive way. I shall rather try to brush in let us say a more impressionistic way a sketch of David Nachmansohn. However I hesitate to talk about David Nachmansohn. The complicity in the work, the pleasure of friendship are secret things rather difficult to pass to others and it is hazardous to draw a portrait in which I might be the only one to recognize David Nachmansohn.

As Goethe, Dear David, you have always wished that memories be creative and that past be evoked only to start life afresh. You do not accept that people be weak and one feels immediately in your company that a certain profoundness of life is possible and to those approaching you, you give indeed the impression that this is in the realm of their possibilities. You are wonderfully exacting but even more for yourself than for the others.

At the risk of tarnishing the glitter of this address I shall not recall the many scientific distinctions and the no less numerous honors that have lighted upon you. I shall first mention, in a rather narcissic way, that you have received an honorary degree from our University. You have also a honorary degree from the Free University of Berlin and Tufts University. You are member of the National Academy of Sciences and several other academies among them the German Academy of Sciences (Leopoldina). You are a Honorary Fellow of the Weizmann Institute of Sciences, Rehovot, Israel and member of the Board of Governors. You have received several medals: the Pasteur medal, Paris; Neuberg Medal, New York and the gold medal, Madrid.

I first met David Nachmansohn in 1955. I had been associated previously with H.H. Ussing, in 1951 and 1955, in Copenhagen where I had done some work related to the active transport of inorganic ions. While using the urinary bladder of the frog as experimental object, I found in 1951, that neurotropic compounds such as atropine, eserine, prostigmine and curare had an effect on the transepithelial potential. I came home in Liège to finish my medical studies with the idea that cell membrane permeability in general could well be controlled by acetylcholine or a closely related system. Therefore it was obvious that the only place to go to become more proficient in the matter, was David Nachmansohn’s laboratory. Thus after having obtained my medical degree and fulfilled my military obligations I went to New York. Immediately I was faced with a striking aspects of Nachmansohn’s personality. The work going on in his laboratory was a multidisciplinary approach to the problem of bioelectrogenesis in conducting membranes and all the efforts of the members of the team had to be centered on that subject matter. I recall vividly the enthousiasm of David Nachmansohn as he was describing his ideas as well as the experimental project in which I had to take part and it was clear to me at that very moment that Nachmansohn’s views regarding bioelectrogenesis were not the result of making a few little improvements and additions to established theories, but by creating new foundations for our views of nature.

This was even more evident to me when I became familiar with the paper that Nachmansohn published in 1943 with Machado. They described the extraction, from brain, of an enzyme (choline acetylase) which, in a cell free solution, acetylated choline on addition of ATP. This discovery, the first acetylation in vitro, came as a shock against the argument of authority that had imposed the concept of acetylphosphate as the general active acetate used in acetylations. This contribution of Nachmansohn must be recognized as a highlight in the history of biosynthesis as clearly established by Florkin in his History of Biochemistry (vol. 33A, p. 33, 1979).

Nachmansohn had worked in Meyerhof’s laboratory for several years on the role of phosphocreatine in muscle contraction. In that sense he had received the seminal influence of Meyerhof’s emphasis regarding chemical and energy coupling in cellular reactions. But he was equally impregnated of the atmosphere of the Kaiser-Wilhelm Institute in Dahlem. In the Twenties, biochemistry was also in full growth and progress in physics and chemistry made available to research workers more and more refined and sensitive methods of investigation. This was certainly the proper conditions for a bright and enthousiastic student to engage in a career devoted to creative achievements.

In the Thirties, one of the most controversial topics was certainly the mechanism of synaptic transmission. Following Dale’s ideas eminent physiologists were indeed prone to accept the idea of neurohumoral transmission though vigorous opposition was manifested by equally competent neurobiologists. Also two different mechanisms were thought to be operative one in nerve conduction and the other in synaptic transmission of impulses.

The contradiction or rather the inadequacy of the concepts prevailing at that time was clearly perceived by David Nachmansohn, who, trained as a biochemist accustomed to think in terms of enzyme action, was rather surprised to notice a complete lack of biochemical approach to such fundamental question. Thus stimulated by the importance of the problem Nachmansohn’s interest grew into what would become a life work shaping a completely new field of scientific interest.

David Nachmansohn came across his first electric fish at the World’s Fair in Paris in the summer of 1937. The spectacular property of certain species of fishes to produce electricity had been known for a long time already in Roman time. Electric fishes had already been used, mainly in the XIX Century when sensitive detecting devices available today were not yet invented. Their powerfull discharge could then be measured with less sophisticated instrument. The analogy of the electric organ with a voltaic pile was even recognized by Volta who called his pile an artificial electric organ. And as we know today, it is even more than an analogy. However little had been done with regard to the biochemistry of the electric organ, when Nachmansohn started to use it as experimental material after his visit at the World’s Fair in Paris. This is when he worked in Arcachon just before the onset of the 2nd World War. As demonstrated by later work and amply illustrated in this meeting, electric fishes have proven to be unique tool to further improve our understanding of the molecular aspects of bioelectrogenesis.

I have already alluded to the strong personality of David Nachmansohn. This is perhaps the most obvious characteristics of a man who has also an extremely well developped sense of humor. The collaborators that Nachmansohn has attracted in his laboratory certainly recall the many jokes, appropriately told to pass a message. For instance to illustrate the hopeless task of trying to convince a stubborn interlocutor, he would tell the story, as a matter of fact a true fable, about the scorpion asking to be carried on the back of a turtle across a river. In the middle of the stream after having delivered a deadly sting to the benevolent reptile, they both drawn. Asked by the turtle why he did that, the scorpion answers: “I cannot help, it is my character!”

Very early in his attempts to resolve the contradictions raised by the interpretation of electrophysiological data, Nachmansohn has stressed the fact that among the cell components, only proteins have the properties that make them particularly well suited to provide proper control for specific cellular function. Based on thermodynamical analysis performed by Wilson and Cabib on the enzyme cholinesterase, the idea was proposed that specific ligand recognition could lead to...

Produkt-Details

• Erscheint lt. Verlag: 24.4.2014
• Sprache: englisch
• Themenwelt: Sachbuch/Ratgeber ► Natur / Technik ► Naturführer
• Themenwelt: Naturwissenschaften ► Physik / Astronomie
• Themenwelt: Technik
• ISBN-10: 1-4831-8985-6 / 1483189856
• ISBN-13: 978-1-4831-8985-7 / 9781483189857