I’m afraid I have something of an ulterior motive in selecting Melvin Calvin as my chemistry hero. There are many brilliant chemists shrouded in the mists of 20th century history, and it was only because of an amusing story I was told by the legendary John Kilcoyne at this year’s Cheltenham Science Festival that I began to take serious notice of Calvin’s work. That said, Calvin is a man worthy of standing alongside some of the other giants of the chemical sciences that have already been featured in this series of blog posts. Most scientists will instantly associate Calvin with the famous biochemical cycle, named in his honour, which he elucidated. In the 1950s, when Calvin carried out his work, little was known about the details of photosynthesis and the idea that carbon dioxide was the feedstock for making plants’ sugary foodstuffs wasn’t widely accepted.
Calvin set about conducting tortuously complex experiments to assess the impact of everything from light, pH, carbon dioxide and oxygen on photosynthesis. All this needed an elaborate array of instruments and Calvin’s 1955 JACS paper – kindly provided for me by Tracey Jenkin at the Worsley Chemical Library at Bristol University – has a figure showing one such set up. It looks like something a stereotypical mad scientist dreamt up and was undoubtedly exacting both to set up and use on a daily basis.
Figure 1 from Calvin's 1955 JACS paper
Although of course I wasn’t lucky enough to ever meet Calvin (he died in 1997), according to John Kilcoyne he was a serious man with little patience for jokes or pleasantries.This contrasted starkly with his graduate student A T Wilson; a bit of a practical joker. Wilson reputedly made a wager with the departmental secretary that he could sneak in a picture of a man fishing in one of the reactors in the diagram without his supervisor realising. He won his bet and the fishing man is still in the diagram. Calvin never found out.
Looking a little closer we can see the little fishing man that Wilson snuck into the paper
Josh Howgego
Tue 19 Jul 2011 at 2:45 am
I burst out laughing at the smart trick which a humorless scientist, observant as he was could not detect! Maybe we need some humor to observe the non-humor in science. Congrats A.T. Wilson!
Thu 12 Apr 2012 at 7:58 pm
So, exactly how does one go about calculating the “Wilson Constant”?
Sat 21 Apr 2012 at 5:02 pm
I’ve been searching for Dr. A.T. Wilson since 1959, when I first read Wilson,A.T. and Calvin,M. (1955) J. Am. Chem. Soc. 77, 5948-5957. In that paper, Wilson and Calvin reported detailed experimental procedures in corroboration of Calvin and Massini (1952) Experientia 8, 445-484.
I wonder if the people in charge of this site would kindly put me in touch with Dr. Wislson, on whose comment above this instant comment is intended.
The reason is, the Calvin cycle – the dark reaction in photosynthesis, which begins with a splitting of the 6-carbon addition adduct into two 3-PGA molecules, was ruled out by Melvin Calvin in his Nobel Lecture. I provide as follows the original papers in support of Calvin’s conclusion against the dark reaction cycle attributed to him.
In the early 1950′s, Wilson, Massini and Calvin reported their finding of carboxylation in photosynthesis as “reaction (L),” i.e., a light reaction, setting the stage for Calvin et al’s celebrated C-14 tracer work for the entire decade of the 1950′s with the reaction scheme for photosynthesis shown below.
In the light, carboxylation results in an asymmetric splitting of the 6-carbon intermediate into one molecule of PGA and another of triose (i.e., a direct photoreduction of carbon to the sugar oxidation level):
RuBP + CO2 ────> Triose →→ Sucrose
|──-> PGA (L)
In the dark, carboxylation results in the hydrolytic splitting of the 6-carbon intermediate into two molecules of PGA:
RuBP + CO2 ────> 2PGA (D)
Calvin’s final work concluding in favor of his finding of reaction (L) is found in Calvin,M. and Pon,N.G. (1959) J. Cellular Comp. Physiol., 54, Suppl. 1, 51-74.
A year later, Bassham, J.A. and Kirk, M. (1960) Biochim. Biophys. Acta, 43, 447-464, confirmed Calvin and Pon (1959) as follows:
“When Calvin and Massini (1952) reported the formation of PGA in an overall reaction requiring ribulose [bis]phosphate and CO2 they proposed that the reaction in the light gave one molecule of PGA and one of triose phophate [reaction (L)] but in the dark gave two molecules of PGA [reaction (D)]. Wilson [and Cavlin (1955)] discussed this possibility further ***. We shall present here an argument, based on kinetic data, which indicates that the carboxylation of Ru[B]P in vivo during photosynthesis gives rise to only one molecule of 3-PGA.”
Accordingly, Calvin in his Nobel Lecture, Calvin, M. (1964) “The path of carbon in photosynthesis.” The Nobel Lecture, delivered on December 11, 1961, From Nobel Lectures, Chemistry 1942–1962. Elsevier Publishing Company, Amsterdam, pp 618–644 at 638, presented the final schematic representation of his finding of reaction (L), in Fig. 20, with the explanation:
“Here [in reaction (D)] the intermediate is split by hydrolysis to two molecules of phosphoglyceric acid. However, in our earlier work the possibility of a reductive fission [in reaction (L)] at the same point to give one molecule of triose and one molecule of phosphoglyceric acid was considered. It was rejected in favor of the hydrolytic splitting because of our failure to find any evidence of the intermediate. However, more recent, very careful kinetic analysis of the carbon flow rates by Dr. James A. Bassham has suggested that the reductive split may indeed participate in the reaction to some extent while the light is actually on.”
In 1988 I, in Fong, Francis K. and Butcher, Karen A. (1988) Biochem. Biophys. Res. Commun., 150, 399-404, showed – in support of Calvin and Massini (1952), Wilson and Calvin (1955), Calvin and Pon (1959), Bassham and Kirk (1960), and Calvin (1964) – the non-equivalence of the “upper” and “lower” 3-C fragments in the 6-C intermediate in the direct reduction, in the light, of carbon to the sugar oxidation level. In 1989, my associates and I published a molecular mechansim for the reductive path of carbon in photosynthesis. See, F.K. Fong, K.A. Butcher, A. Agostiano, M. Della Monica, M.S. Showell, and J. V. Schloss (1989), “Coupling Between the Light and Dark Reactions of Oxygen Evolution and CO2 Fixation in Photosynthesis: Early Experiments in Photosynthesis Revisited,” in Enzymatic and Model Carboxylation and Reduction Reactions for Carbon Dioxide Utilization, Eds. M. Aresta and J.V. Schloss, Series C: Mathematical and Physical Sciences – Vol. 314, NATO ASI Series Advanced Science Institutes Series, Kluwer Academic Publishers, Dordrecht/Boston/London.
To summarize, by Calvin’s original papers, the carbon fixation reaction in photosynthesis does not occur via the Calvin cycle. Following the work of Wilson, photosynthetic carbon fixation is given by reaction (L), which is neither dark nor cyclic, a reaction in which the carbon is reduced, in the light, directly to sugar without the intervention of the NADPH (for reducing equivalents) and ATP (energy for overcoming activation barriers in the dark reaction) from the Z-scheme. Dr. Wilson was the student in Calvin’s group who first did the very important experiments in confirmation of the seminal proposal of reaction (L) by Calvin and Massani (1952).
For the reasons given above, I would appreciate the opportunity to discuss this matter further with Dr. Wilson.
Francis K. Fong
P.S. In 1978, at the behest of Deputy Energy Research Director Doug Pewitt, I personally met with Dr. Calvin for a day-long conference at Asilomar, California, specialized to an in-depth discussion of Wilson and Calvin (1955), Calvin and Pon (1959) and Bassham and Kirk (1960) and the consequences of the community’s general perception of the Calvin cycle as tried and true. You can find a detailed investigation addressing the origins of the Calvin cycle on NSFfunding.com’s Website @ http://www.nsffunding.com. NSFfunding.com is a New Organization approved by the U.S. National Science Foundation for the express purposes of unraveling the Calvin cycle.
Mon 23 Apr 2012 at 9:21 am
Hi Francis,
Unfortunately we don’t have any contact details for Dr Wilson. He was not contacted during the preparation of this article and did not contribute to it directly.
Sorry we can’t be more helpful,
Phillip
Mon 14 May 2012 at 11:43 am
Haha! My friends and I would often make bets that we could slip song lyrics, silly sentences and other stuff into our school essays. But to publish this in an academic journal?! Mr Wilson is the true hero!
Thu 28 Jun 2012 at 6:03 am
That’s hilarious! I’m really surprised he never saw the fishing man, it’s a little obvious
. Glad to hear of his accomplishments and yes we need more heroes in today’s modern chemistry fields. Thanks for the great writeup. – Serge
Fri 29 Jun 2012 at 11:23 pm
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