Talk:Peter D. Mitchell

Untitled
Well, Saier's biography of Peter Mitchell has many good pictures in it, and I did consider to take some pictures from there. But the problem is that they are relatively recent (after 1923 anyway), so I decided against that because of copyright issues. If you want to look into that, perhaps send an email to Saier to ask him about it, be my guest. JdH 10:37, 8 May 2006 (UTC)

Can this be merged with http://en.wikipedia.org/wiki/Peter_Mitchell_%28Chemist%29 ?

Yes. If you need help, let me know. --JWSchmidt 16:46, 27 January 2006 (UTC)

Completed merge JDH 9:45, 28 January 2006

The Older Article Was Better
The present version of this article gives an entirely false account of the history of science. The article begins “... the mechanism by which ATP was created in the [sic] mitochondria was assumed to be by [sic] substrate-level phosphorylation.” Grammatical quibblings aside, this statement is factually incorrrect.

The actual situation in the 1960s was summarized by Nicholls and Ferguson (Nicholls DG, Ferguson SJ. Bioenergetics 2. Academic Press, 1992) as follows:


 * By analogy to the only reactions in which a detailed mechanism of ATP synthesis was available, namely the phosphorylations (traditionally known as substrate-level phosphorylation) in glycolysis and the citric acid cycle in which thioesters participate as reaction intermediates, it was reasonable to expect that the common energy-transducing entity would be a chemical ‘high energy’ intermediate, usually referred to by the short-hand ‘squiggle’. Despite a number of false starts, no 'squiggle' was ever found.

In other words, the mechanism by which ATP was created in mitochondria was entirely unknown.

The article goes on “...At the time, oxidative phosphorylation was unknown as a biochemical mechanism to make ATP.” Actually, oxidative phosphorylation was well-known at the time. It was, in fact, was the central focus of biochemical research at the time. Biochemists knew that mitochondria did this thing, but they didn’t know how they did it. It was the mechanism that was unknown, not the phenomenon.

Nicholls and Ferguson continue:


 * As so often in science, the solution was simple and elegant. Peter Mitchell...

and they go on to discuss Mitchell’s unique, original, and extremely controversial “chemiosmotic theory.” Readers who would like additional information about Mitchell’s almost fairy-tale story (a young biochemist discovers the secret of life, is universally scorned and neglected by organized science but continues to pursue his vision at great personal expense, and 20 years later is vindicated and receives the Nobel Prize) should consult Gilbert and Mulkay’s sociological analysis (Gilbert GN, Mulkay M.  Opening Pandaora’s Box. Cambridge University Press, 1984). The book contains extensive quotations from the “grand old men” of biochemistry at the time, all of whom are now thoroughly discredited.. It is a wonderful cautionary tale about the importance of keeping an open mind in science.

This Wikipedia article is about Peter Mitchell and the history of science. It is not an article about oxidative phosphorylation or modern biochemistry. Nevertheless, Mitchell’s “theory” ( and it is a “theory” in the same sense that evolution is a “theory”) can be explained in modern terms to the interested reader. Unfortunately, the article as it stands presents an incorrect and misleading explanation.

The article says “...the movement of ions across a membrane had an electrochemical potential to do work that could be utilized to produce ATP.” Of course, this is nonsense. It is the charge separation and difference in the concentration of ions that has the potential to do work, not the movement of ions. The exact mechanism by which this electrochemical (“chemiosmotic”) potential is used to produce ATP is another story (also a Nobel Prize winner) that can be pursued by looking up “ATP synthase” in Wikipedia.

On the whole, I think that the article should be reverted to an earlier version. I also think that the biography of Peter Mitchell should be expanded, not deleted. Earlier versions of this article contained a lot more biographical information, and this is precisely the information I would expect in an article about Peter Mitchell. Btarski 21:08, 16 August 2006 (UTC)


 * I see no gross factual errors in the section on the Chemiosmotic hypothesis; perhaps some minor semantic issues, but that is all. David D. made some editorial changes a few months back, and I thought that those changes were really improvements. He took out some peacock words, and made some other improvements, but the basic story did not change. I take it that you disagree with the sentence Mitchell realised that the movement of ions across a membrane had an electrochemical potential to do work that could be utilised to produce ATP. That sentence is correct in that ions do have to move across the membrane in order to mobilize the electrochemical energy to synthesize ATP; however, the words electrochemical potential are somewhat confusing in this context. Some minor editing of that sentence should fix that. The bigger issue really is that the paragraph on electrochemical potential has a lot of overlap with the articles on electrochemical potential, membrane potential, and oxidative phosphorylation. So I think that all what should be mentioned in this article is a couple of sentences summarizing Mitchell's contribution to the field, with proper wikilinks to those other articles. Most of the paragraph on electrochemical potential can be merged into the article on electrochemical potential. I agree that this article should focus on Mitchell's biography; this is not the proper place for an in depth discussion of membrane potentials and all that. But AFAIK little or no biographical data has been removed since I merged Peter Mitchell (chemist) into this article, back in January. Unfortunately, little was added since then either. So yes, I wholeheartedly agree that the biographical section needs extension; the question is who is going to do that. Milton Saier's . Peter Mitchell Biography contains a lot of good information. JdH 22:20, 16 August 2006 (UTC)

My changes were more to get rid of the POV and the stylistic language. I removed this following sentence, for example:
 * "it was well known in the 1960s that ATP was the energy currency of life, but the mechanism by which ATP was created ("oxidative phosphorylation") was entirely unknown and quite mysterious."

Froim what you have written above i don't think this is the version you want to revert to. Which is your preferred version? Why don't you just go in and correct the current version? Some of your issues mentioned above would be quite trivial edits. For the record i dod not remove any of his biographical information. i look forward to see how you improve this article. David D. (Talk) 22:51, 16 August 2006 (UTC)


 * Btarski, what i find very strange is that you added the sentence I mention above. Do you think that stylistically "entirely unknown and quite mysterious" is appropriate language? I also think you are making a big deal over the substrate level phosphorylation. The paragraph from Nicholls and Ferguson that you quote above seems to confirm that the scientists of the time were doing experiments to try and find evidence for substrate level phosphorylation.  The fact they had not found them does not mean they had stopped looking does it? I assume what stopped them looking was Mitchell's hypothesis that did a much better job of accounting for all the available data.  I acknowledge that I have not read a single Mitchell biography but it is not that far from what your own preferred position. Do we know for sure that they had absolutely ruled out substrate level phophorylation as a mechanism before the 60's? Again, i am open to any changes you wish to make.
 * While you are here, do you plan on working on the ETC article? You mentioned six weeks ago that you wanted to reorganise the article but I have not seen any edits since then? David D. (Talk) 23:07, 16 August 2006 (UTC)

Clarification: Btarski
Let me try to make my comments perfectly clear. It is important to distinguish between the history of science, on the one hand, and modern scientific understanding on the other.

For example, in reading about Copernicus, it is important to understand that most people at the time believed that the Sun revolved around the Earth. It was self-evident. In order to appreciate Copernicus you have to understand the historical context. Otherwise, it’s like “duh, everybody knows that”.

The present article is historically incorrect. It confuses modern understanding with the historical context. I supplied a few references, but this is just the tip of the iceberg. Peter Mitchell was one of those rare geniuses who produced a paradigm shift in his own lifetime. The only comparable biologists I know of are Barbara McClintock, Watson & Crick and Lorente de No.

The main point of my comments has to do with the history of science, not with “Science” itself. History is a specialized field, and unless one claims to be an expert, one should leave it to the experts.

I regret quibbling about the description of Mitchell’s theory, which is framed in modern terms in the article. The article’s description is preposterous from a thermodynamic viewpoint, but the number of Wikipedia readers who know anything about thermodynamics, or who could care less, is probably vanishingly small. It makes very little difference how a summary of chemo-osmosos is presented in a Biography of Peter Mitchell. The point should be historical accuracy.

I learned a long time ago that Wikipedia readers with a degree in chemistry experience an overwhelming compulsion to revise chemistry articles in order to fit them into (or to force them to conform with) their own personal knowledge of chemistry. In general, this is a good thing, one of the main strengths of Wikipedia. However, such revisions are entirely inappropriate in an article on the History of Science, such as a biographical article on Peter Mitchell. The emphasis should be on the historical context, not on modern understanding.

I do not want to get involved in a discussion of how stupid it is to consider ion movements, as opposed to electrochemical potential gradients, in a discussion of the Mitchell Hypothesis. Peter Mitchell knew a lot more about thermodynamics than I ever will (it was his field of specialization) and I would recommend that technical descriptions of Mitchell’s proton-motive force be relegated to other articles. There is no sense in quibbling about thermodynamics in this article.

My point is that the article is supposed to be a biography of Peter Mitchell, not a forum for discussion and endless revisions of the modern viewpoint. It is an historical article, and Mitchell’s Nobel-Prize-winning insight should be acknowledge for what it was: a landmark discovery in the history of science. It should be prsented in its proper historical context.

I very much appreciate your kind words, but I am not willing to undertake a major revision of this article. My suggestion is to revert it to an earlier, more historically accurate version.

Btarski 00:26, 17 August 2006 (UTC)

Which version are you wishing to revert too? And what about the substrate level phosporylation? That is definitely important from a historical context since it was the working hypothesis for many in the field at the time. I am still not clear if you saying that most people had already discounted it as a mechanism and were searching for the 'mysterious', or whether they were still seeking alternative high energy metabolites. David D. (Talk) 04:30, 17 August 2006 (UTC)


 * If the purpose of that section is to place Mitchell's contribution in a historical context then I believe it misses the most important point. Which is that the "scientific establishment" of the time did not accept his ideas, and Mitchell had a hard time to get his papers published in peer reviewed journals. Saier's biography on Mitchell has the following about that issue:
 * Because Peter's scientific ideas were not in general acceptance by the scientific community, the peer review system utilized for evaluation of submitted manuscripts for publication in scientific journals sometimes resulted in harsh criticism of the ideas and experimental results generated at Glynn. Additionally, the scientific journals sometimes had rigid requirements of style and length which proved annoying. In response, Peter, who had written lengthy treatises on his ideas regarding oxidative and photosynthetic phosphorylation had his own articles and books privately printed, sending these primarily to friends and colleagues who were favorably inclined to his ideas.
 * and
 * The more important and novel a theory is, the more it is likely to be attacked and berated. Two of the more vociferous critics of the first chemiosmotic hypothesis were Britton Chance in Philadelphia who for a long time believed in direct chemical coupling as an explanation for oxidative phosphorylation and Paul Boyer in Los Angeles who first believed in chemical coupling and then switched to a "conformational" model in which electron flow through the electron transfer chain was suggested to induce membrane protein conformational changes. 
 * The controversy was resolved in the well-known joint publication (Boyer, P.D., B. Chance, L. Ernster, P. Mitchell, E. Racker and E.C. Slater. 1977. Oxidative phosphorylation and photophosphorylation. Ann. Rev. Biochem. 46:955-1026.), in which the general acceptance of the essential principles of Mitchell's chemiosmotic hypothesis was announced. JdH 10:08, 17 August 2006 (UTC)

I agree.

ATP was discovered in the 1940s. In the 1950s, the mechanisms of substrate-level phosphorylation were discovered. Unfortunately, these accounted for only a small fraction of the energy produced by the cell. The vast majority of ATP is produced by oxidative phosphorylation. It was initially assumed that the mechanism of oxidative phosphorylation would be similar to the mechanism of substrate-level phosphorylation (These and subsequent quotations are from Gilbert and Mulky's Opening Pandora's Box):


 * They were quite convinced that electron transport was going to be just as easy a thing to sort out as glycolysis in solution. You had to have a series of carriers.  Admittedly these things were not readily purified, but it became apparent that they reacted in an orderly sequence in the membrane.  The game was spot the missing factor.


 * I think at the time the general view in the field was that you could make ATP in a soluble system, so all you had to do was throw in some cytochrome C, take ADP and phosphate, and then take a proposed intermediate enzyme, which made ATP.

In the 1960s it became apparent that this approach was not working, and that some other mechanism must be involved:


 * I worked on that system for the better part of three years . . . and the net result is that we could never really show any specificity of the enzyme in terms of its interaction with cytochrome C . . . It never occurred to me that people could say things like this, very important people, and turn out to be completely wrong . . . I thought well, the field is really screwed up . . . and I didn’t believe half the stuff that was published, because I saw that we were dealing in this field with people who had very strong egos, who were trying to get an answer very rapidly, and who weren’t cautious about what they were trying to do


 * During this same period, two other theories to explain oxidative phosphorylation were proposed . . . [the] “conformational coupling” hypothesis, formulated in 1964, suggested that the energy necessary for the formation of ATP was not stored as a chemical intermediate or as an electrochemical gradient, but as changes in the conformation or shape of the molecules in the mitochondrial membrane . . . [In another theory] the coupling between the respiratory chain and ATP synthesis was conceived in terms of mechanical movements of the membrane.

It was during this period that Mitchell formulated his chemiosmotic hypothesis. The first paper outlining his ideas in relation to oxidative phosphorylation was published in 1961. The initial reaction to Mitchell’s theory was less than enthusiastic:


 * It was during this period of time when I came in 1964 that everybody was thinking of chemical mechanisms for how ATP would be made in a soluble system. And it was only then, at that stage of the game, that [Mitchell] came out with his early papers in Nature, and then finally those two little books that he sent me, in which he emphasized that all biological systems that carry out the synthesis of ATP are membrane systems and they are all closed systems and that nobody had ever isolated a chemical intermediate before and so maybe they didn’t exist.  Which was a little far-fetched, because you’ve got to have chemical intermediates to make ATP.


 * When I came here, I knew nothing. All the seminars they had here were just incomprehensible, but it was clear that everybody was against [Mitchell] heavily at that time and he wasn’t doing too well.  There was a lot of evidence against his ideas.  The movement toward accepting it . . . was due to a lot of young people coming in.


 * Until the 70s, at least in some of the major labs in the field, nobody had made the effort to understand the chemiosmotic hypothesis. It’s pretty obvious from the kind of things that they were saying at conferences or in papers, and a number of people who “disproved” the chemiosmotic hypothesis that they were just making trivial physical-chemical mistakes, that sort of thing.

In 1978, Mitchell was awarded the Nobel Prize.

Btarski 20:13, 19 August 2006 (UTC)


 * We are making some progress :-) But I believe that there is more behind those "Oxphos Wars" that raged for 15 years from 1961 to 1975. Part of what was going on is that Mitchell's background was different: he was a microbiologist who was interested in membrane physiology, while his major opponents were biochemists or biophysicists. So Mitchell knew that there were differences in ion concentrations across cell membranes, and from basic thermodynamic principles one has got to conclude that it is going to take energy to maintain those concentration differences. From those considerations Mitchell came up (late 1950s, hence preceeding his chemiosmotic hypothesis) with something he called Vectorial chemistry. This is a generalized concept of how he thought that enzymes might work: substrates come in at one side of the enzyme, move through a channel, and the enzyme products come out at the other end. A fundamental coupling of transport and chemistry so to speak. Ion pumps which are embedded in a cell membrane are a special case of this vectorial chemistry. AFAIK Mitchell believed in this vectorial chemistry until the end, see eg,  and  The really interesting issue is that this vectorial chemistry is totally wrong: That is not how enzymes work. So the  'grand old men' were absolutely right in opposing that. Recent work has demonstrated that F0F1-ATP synthase in fact works like a nanoscale protein motor, see: e.g.  and  So here is the real kicker: Out of a hairbrained idea that was totally wrong (=vectorial chemistry) came something that was absolutely right (=chemiosmotic hypothesis) JdH 14:37, 20 August 2006 (UTC)

Hmmm. ..

Your characterization of Peter Mitchell as being right for the wrong reasons is new to me. It is a delightful insight into history, and my initial reaction is that you are probably right.

My own personal take on Mitchell is much more in the realm of hero worship. I regard him as one of the great geniuses in the history of science.

Before getting in to my personal views, however, I would like to take a brief digression into the Wikipedia article on Peter Mitchell. I started off by saying that the previous versions were better, and I think that I can now support this assertion when it comes to the subject of oxidative phosphorylation:

REVISION 1.0.0
The present version:


 * In the 1960s, ATP was known to be the energy currency of life, but the mechanism by which ATP was created in the mitochondria was assumed to be by substrate-level phosphorylation. Mitchell’s chemiosmotic hypothesis was the basis for understanding the actual process of oxidative phosphorylation.

The previous version:


 * It was well known in the 1960s that ATP was the energy currency of life, but the mechanism by which ATP was created (“oxidative phosphorylation”) was entirely unknown and quite mysterious.

I think that the current Wikipedia version states the facts incorrectly, and that the previous version states the facts more accurately. It is true that the state of the art in the 1950s (not the 1960s) was that “substrate-level phosphoylation” was assumed to be the only possible mechanism of ATP synthesis. By the 1960s, however, it had became obvious that this “theory” was a dead end, and that a new theory was needed.. The mechanism of ATP synthesis was quite mysterious. One experiment after another failed to find any trace of the classical “high-energy intermediate” (also known as “squiggle”) that would explain oxidative phosphorylation. This is where Peter Mitchell came in.

I can see how a teacher might, for didactic purposes, simplify history for his students by saying that the ongoing theory at the time was substrate-level phosphorylation. But in fact there was no ongoing theory at the time. To say that substrate-level phjosphorylation was “assumed to be” the mechanism of ATP synthesis is a mischaracterization of the “Oxphos Wars.” Students who have been taught this incorrect piece of historical trivia need to learn a little more about the subject before they start revising Wikipedia articles.

I recommend reversion to a previous version of the article.


 * Too be frank your criticism of my edits is getting very personal. I am happy to work with you here but can you stop with this kind if stuff: "need to learn a little more about the subject before they start revising Wikipedia articles."? This is an ad hom argument and is pretty unwarranted given the subtlty of your criticism. I think what I wrote can be improved but i think if we are going to work towards improvement, just reverting to your old version does not cut it. There were good reason i made the edits throughout the article, primarily because your admitted hero worship was obvious.  It was too POV for an encylopedic content.


 * With regard to the sentence you discuss above. The facts as stated in your own version seem to be unclear, for example: "but the mechanism by which ATP was created (“oxidative phosphorylation”)". This gives the impression that all ATP comes from oxidative phosphorylation. Obviously this is not what you meant but it's how it comes across. The following part of the sentence continues, "was entirely unknown and quite mysterious." In my opinion this is too much hyperbole and should be toned down. Some thing along the lines of: "by the 1960's scientists had failed to discover a ............ and were struggling to identify the mechanism for the ATP produced during aerobic respirtation".  That is just off the top of my head, but it seems a more appropriate style for an encylopedia. David D. (Talk) 03:59, 21 August 2006 (UTC)


 * Thinking a bit more about this: I think the problem in the early 1960s was that the field of ox phos had been subdivided into little pieces. There were people who were interested in the bioenergetics; they wanted to understand how the energy is transduced for synthesizing ATP. Then there were enzymologists, who wanted to understand the protein structure and the mechanism of the specific enzymes involved. And then there were microbiologists who were interested in membrane physiology and transport processes. So all the pieces were in place, and all the right questions were being asked, but what was lacking was the big picture, the vista so to speak. People couldn't see the forest through the trees. Biochemists and biophysicists like to analyze the problem in separate little pieces, and after they understand the little pieces integrate it into a big picture. But that analytical approach does not work for ox phos. Mitchell's chemiosmotic hypothesis provided the big picture, but people had a hard time to recognize that because he did not provide the answer for the specific sub-questions they were interested in. JdH 15:22, 21 August 2006 (UTC)

Discussion (Cont’d)
Peter Mitchell may have been right for the wrong reasons, but this in no way detracts from his genius. You mention his background. I think that his background is well worth knowing about in more detail.

As a graduate student at Cambridge, Peter Mitchell


 * . . . would carry out a large number of small, rather inconclusive experiments which enabled him to develop his theory of what was occurring. Then he would design one massive all-inclusive experiment based on the results of all the preliminary tests – and that, if it worked, was that.  To any one outside of the department, much of his early work seemed to be incomplete because he left out those tests or controls which were discarded during the preliminary work.  I well remember sitting next to Hans Krebs at a meeting of the Biochemical Society when Peter first gave a major paper on his work on energy transfer . . . Krebs steadily became more and more incensed and muttered  “But in he hasn’t done the controls.”

Mitchell submitted a PhD thesis that was rejected. He flunked Cambridge.

Apparently only a few pages of his original thesis survive, but I think they are extremely telling:


 * In the second paragraph, Mitchell cites Heraclitus, along with Seneca’s comments on Heraclitus’s famous dictum that one cannot step into the same river twice.  He notes that the same is true of a human, whose identity persists but whose substance is constantly being changed.  In the same paragraph he cites Walter de la Mare’s little verse about Miss T. that includes the lines “Whatever Miss T. eats, turns into Miss T.” . . . This was followed by a mathematical theory of diffusion and distribution of substances within cells . ..

During his philosophical period, Mitchell sought the professional opinion of the Department of Philosophy at Cambridge. He is quoted as saying


 * There was a man called Wisdom in those days who more or less told me I was a nit.

In other words, Mitchell was a serious contender from the outset, a fact which a number of the Grand Old Men in science at the time came to appreciate only in retrospect, to their everlasting regret.

The above quotations are from Wandering in the Gardens of the Mind, a 324-page biography of Peter Mitchell by John Prebble and Bruce Weber (Oxford University Press, 2003). This, together with Opening Pandora’s Box, contains essentially all of the original source material that is available to the general reader (e.g. yours truly). If I get around to it I would like to make a further case regarding the description of Mitchell’s theory in the present version of the Wikipedia article, but for the moment I stand by my original assertion that the entire article should be reverted.

Btarski 03:23, 21 August 2006 (UTC)


 * I find it hard to find objective evaluations of Mitchell's contributions; the people who write the histories were too much personally involved. In particular, I would like to hear the story from "the other side", i.e. from Chance and Boyer, if it exists. Be that as it may, there is a highly unusual comment from Bo G. Malmström in Nature . Unusual in the sense that Malmström was the chairman of the committee that recommended to award the 1978 Nobel Prize for Chemistry to Peter Mitchell. I always thought that the Nobel prize committees never give a public justification for their recommendations, but in this case they made an exception. The bottomline: The committee was well aware of the fact that Mitchell was wrong about how the proton gradient is created (proton pumps rather than redox loops) and how it is utilized to make ATP (conformational coupling rather than mass action). This is why the academy's citation read rather vaguely "for the contribution to the understanding of energy transfer through the formulation of the chemiosmotic theory". JdH 07:05, 21 August 2006 (UTC)

I stand corrected. Peter Mitchell was right for the wrong reasons.

This of course makes a description of the original chemiosmotic hypothesis rather difficult. We have to distinguish between what was right (his Nobel-winning insight into the role of membranes in biological systems) and what was wrong (almost all of the details).

Now for a brief digression. ..

Revision 1.0.1
One way around this is to avoid any detailed description of the theory. This was the approach taken in a previous version:


 * It was also well known in the 1960s that all living cells had a membrane potential, interior negative to the environment, such that both electrical forces (the attraction of plus to minus charges) and thermodynamic forces (the tendency of a substance to diffuse downhill from regions of higher concentration) had the potential to do work, to produce energy.


 * Peter Mitchell wondered why this was so. Why do all living cells have membrane potentials?


 * He went on to prove that ATP was created by this electrochemical gradient.

An alternate approach is to describe Mitchell’s theory in detail (bearing in mind that this article is supposed to be a biography of Peter Mitchell, not a scientific treatise). The present version of the article takes the second approach:


 * Mitchell realized that the movement of ions across a electrochemical membrane potential could provide the energy needed to produce ATP. His hypothesis was derived from information that was well known in the 1960's.  He knew that living cells had a membrane potential; interior negative to the environment.  The movement of charged ions across a membrane is thus affected by the electrical forces (the attraction of plus to minus charges).  Their movement is also affected by thermodynamic forces, the the tendency of substances to diffuse from regions of higher concentration.  He went on to prove that ATP synthesis was coupled to this electrochemical gradient.

Unfortunately, this description is wrong, both in terms of Mitchell’s original theory and in terms of modern versions of the theory.

Lehninger (Principles of Biochemistry, 4th ed., 2005) provides the following summary of chemiosmosis:


 * The electrochemical energy inherent in the difference in proton concentration and separation of charges across the inner mitochondrial membrane – the proton-motive force – drives the synthesis of ATP as protons flow passively back into the matrix through a proton pore associated with ATP synthase.


 * Although ATP synthase equilibrates ATP with ADP + Pi, in the absence of a proton gradient the newly synthesized ATP does not leave the surface of the enzyme. It is the proton gradient that causes the enzyme to release the ATP formed on its surface . . . For the continued synthesis of ATP, the enzyme must cycle between a form that binds ATP very tightly and a form that releases ATP.

In general I would recommend the former approach in a Wikipedia article intended for the general public. The subject rapidly becomes very technical and very complicated. I think it would be better to link to a discussion of chemiosmosis rather than to attempt one in this article.

I recommend reversion to a previous version.


 * flow passively back into the matrix!!?? I find it hard to believe that Lehninger said a silly thing like that. Unfortunately I don't have the 2005 version of Lehninger's book, so I can't check out what the context is of that statement; he is got to be smarter than that! Please check out Capaldi's and Aggeler's review: for an explanation of the mechanism of F(1)F(0)-type ATP synthase. The emerging consensus is that the enzyme is constructed as two rotary motors, one in the F1 part that links catalytic site events with movements of an internal rotor, and the other in the F0 part, linking proton translocation to movements of this F0 rotor. What those protons do when they flow back is turn the F0 rotor which then turns the F1 rotor; i.e: The electrochemical energy is used to drive the conformational changes of the F1 subunit during ATP synthesis. If those protons were to flow passively back the electrochemical energy would be lost, and no ATP would be synthesized. JdH 06:34, 22 August 2006 (UTC)


 * I don’t think it’s as bad as all that. I took it to mean that Lehninger was contrasting “active transport” (the proton pump) with “passive transport” (movement down electrical and concentration gradients).  An old distinction, to be sure, but then Lehninger is no spring chicken.


 * “Passive” movements also have an associated Gibbs free energy change that can be coupled (by a clever enzyme) to a conformational change. Btarski 12:16, 22 August 2006 (UTC)


 * That is muddled language; can we at least agree that we will use unambiguous language to explain what is going on? The version you want to restore states "He went on to prove that ATP was created by this electrochemical gradient." That is sentence is ambiguous at best, and plain wrong at worst. "Gradients" or "potentials" don't create ATP or anything else for that matter. Neither do apples that hang in trees: it is only after they fall from the tree on somebody's head that they perform mechanical work, and trigger a response. JdH 12:37, 22 August 2006 (UTC)


 * Good point. How about "He went on to show that the energy of this electrochemical gradient was used to make ATP." ? Btarski 19:37, 22 August 2006 (UTC)

Discussion (Cont’d)
I think that the essence of Mitchell’s theory was the recognition that biological membranes (and hence “vectors” across membranes) play a central role in all living organisms.

In the 1960s, the controversy over Hodgkin and Huxley’s theory of the action potential had finally been resolved in their favor. Every biologist in the1960s knew about this, but only one (Peter Mitchell) took the next logical step. Why do all cells, not just neural cells, have a membrane potential?

Mitchell’s “vectorial” theories supplied the missing piece in what was then the main conundrum in an entirely separate area of science, the biochemistry of ATP synthesis. To find the “squiggle,” the high-energy intermediate, the biochemists needed to look no further than cell membrane itself, which already had a built-in energy potential.

Btarski 20:34, 21 August 2006 (UTC)