Photosynthesis Research 54: 1–3, 1997. 1c 1997 Kluwer Academic Publishers. Printed in the Netherlands.

Obituary: A remembrance of Melvin Calvin

Melvin Calvin (1911–1997)

After a distinguished career of research and teaching,Melvin Calvin died in Berkeley, California on 8 Jan-uary 1997, at the age of 85. Throughout his life, Calvinexhibited an intense curiosity that drove his scientif-ic research. Although he may be best known for hiscontributions to our knowledge of photosynthetic car-bon dioxide fixation and reduction, for which he wasawarded the Nobel Prize in Chemistry in 1961, hisinterests were much broader and included investiga-tions on chemical evolution, brain chemistry, oncolo-gy and solar energy conversion (Calvin 1989; Bassham1997).

Calvin’s inquiries into CO2 fixation began in themid-1940s. When radiocarbon, 14C, became available

at the University of California Radiation Laboratory,Calvin’s laboratory developed methodology for feed-ing algae 14CO2 and analyzing radioactive productsformed as a function of time. The small amounts oflabeled intermediates were detected and their concen-tration determined using two-dimensional paper chro-matography. Similar methodologies were subsequent-ly adapted by other biochemists and applied to thestudy of many metabolic systems. From the labelingpatterns observed, the CO2 fixation and reduction path-way was delineated by Calvin and coworkers, especial-ly Andrew A. Benson and James A. Bassham.

Calvin’s interest in photosynthesis extended to allaspects of the phenomenon and in the time period

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from 1956 to 1970, many pioneering experiments wereconducted to characterize the primary photochemi-cal events. His laboratory was one of two that firstapplied the new method of electron paramagnetic res-onance (EPR) to photosynthetic systems (Sogo et al.1957). These measurements showed there were twokinds of organic free radicals produced as a result oflight-absorption, one of which appeared to be either anone-electron reduced or oxidized chlorophyll species.Pursuit of such studies eventually led to the assign-ment of one of these signals to a pair of chlorophyllmolecules which served as the primary electron donorin Photosystem I (Norris et al. 1971), and the secondsignal was eventually assigned to an oxidized tyrosineside chain in the reaction center protein of PhotosystemII (Barry and Babcock 1987).

Also developed in Calvin’s laboratory during thisperiod was the extension of the redox bufferingmethod, initially introduced by Bessel Kok (Kok1961), as a general method for the discovery and char-acterization of electron transport components in theirin vivo state. These studies led to the measurementof the midpoint potential of both the primary electrondonor (Loach et al. 1963) and the first stable electronacceptor (Loach 1966) in bacterial photosynthesis.

As was characteristic of Calvin’s laboratory, new-ly developing spectroscopies and methodologies werequickly adapted to the study photosynthetic systems.In addition to the two examples given above, one fur-ther example of a spectroscopic method first applied tophotosynthetic systems in Calvin’s laboratory was thatof circular dichroism (CD). Measurements of CD spec-tra of material from photosynthetic bacteria, as well asfrom oxygenic organisms, provided new insights intothe organization of chlorophyll in reaction center andlight-harvesting complexes (Sauer et al. 1968).

Stemming from Calvin’s early training and research(some of which was involved with the ManhattanProject) was a strong interest in chelate complexes,metalloporphyrins and the development of model sys-tems. We would probably now refer to this area ofresearch as one focusing on biomimetic models or onbiotechnology. Whether this work was driven by thedesire to understand the role of manganese in oxy-gen evolution or to develop new catalysts and pho-tocells, his research career is sprinkled with manyprojects involved in studying metalloporphyrins andtheir derivatives. Many people trained in his laborato-ry in these areas have continued to develop and extendthese fields.

Even though achievements such as those citedabove would seem to be of great significance, perhapsthe most important legacy from Calvin is in the wayhe organized his research endeavors and trained andstimulated the people with whom he worked. Calvinwas one of the first (if not the first) proponents ofproviding a working environment to enhance commu-nication between a diverse group of scientists. Thiswas achieved by utilizing large research laboratoriesin which individual work areas were on the periphery,but key supplies and refreshments were located in themiddle. The idea was that people should frequentlytalk about their research and be informed about theactivity of others in the lab. The second componentwas that the people Calvin recruited into his laboratorycame with diverse training from all over the world –physicists, chemists, biologists, theorists, instrumentengineers, etc. The concept of the cross-fertilization ofideas was a daily expectation in Calvin’s group. Thisconcept worked so well that many new laboratoriesand buildings are now being constructed in ways thatare strikingly similar to Calvin’s early model.

Also contributing to the dynamics of his laborato-ry was his direct interaction with the group. Althoughit was a large group, whenever one was getting newresults, you could expect to see a lot of Calvin. Hisexcitement, enthusiasm and endless questions provid-ed much stimulation. During my tenure in his labo-ratory, I learned many things from him. One lesson Ilearned, he probably didn’t know he was teaching. Asis probably true of most people, I have always beenvery afraid of appearing stupid in front of groups ofpeople – so much so, that I would seldom ask ques-tions. Once a week, the entire biodynamics laboratorygroup met for discussion of an appropriate topic ofresearch. At these meetings, I was at first astonishedat some of what I considered to be ‘really dumb ques-tions’ that Calvin would ask. Just about the time I wasbeginning to wonder how he ever got to the positionhe held, he would make a deeply insightful observa-tion or comment. He gave me permission to show myignorance, and therefore, to learn and to contribute.

Perhaps the best measure of the impact a personhas had on a field is to examine the contributions madeby people who were trained in their laboratory. In thecase of Calvin, if one listed independent investigatorswho were trained, or whose mentors were trained, inCalvin’s laboratory and who have made important con-tributions to an area of Calvin’s interests, for examplethe primary photochemical events of photosynthesis,

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this list would likely include about one-fourth of theactive people in the area.

I received several gifts and have many fond mem-ories from my two years in Calvin’s laboratory. Theseinclude many long-lasting friendships, as well as expe-riencing the fun and excitement of research. Perhapsthe image of Calvin that is most appropriate was bestexpressed by a colleague. He described Calvin as averitable bouncing ball, full of energy and new ideas –perhaps a super ball!

Paul LoachNorthwestern University

Dept. Biochem., Mol. Biology & Cell Biol.2153 Sheridan Rd.

Evanston IL 60208-3500USA

References

Bassham JA (1997) Obituary: Melvin Calvin 1911–1997. Photo-chem Photobiol 65: 605–606

Barry BA and Babcock GT (1987) Tyrosine radicals are involved inthe photosynthetic oxygen-evolving system. Proc Natl Acad SciUSA 84: 7099–7103

Calvin M (1989) Forty years of photosynthesis and related activities.Photosynth Res 21: 3–16

Kok B (1961) Partial purification and determination of oxidation-reduction potential of the photosynthetic chlorophyll complexabsorbing at 700 m�. Biochim Biophys Acta 48: 527–533

Loach PA (1966) Primary oxidation-reduction changes during pho-tosynthesis in Rhodospirillum rubrum. Biochemistry 5: 592–600

Loach PA, Androes GM, Maksim AF and Calvin M (1963) Varia-tion in electron paramagnetic resonance signals of photosyntheticsystems with the redox level of their environment. PhotochemPhotobiol 2: 443–454

Norris J, Uphaus RA, Crespi HL and Katz JJ (1971) Electron spinresonance of chlorophyll and the origin of signal I in photosyn-thesis. Proc Natl Acad Sci USA 68: 625–628

Sauer K, Dratz EA and Coyne L (1968) Circular dichroism spec-tra and the molecular arrangement of bacteriochlorophyll in thereaction centers of photosynthetic bacteria. Proc Natl Acad SciUSA 61: 17–24

Sogo P, Pon NG and Calvin M (1957) Photo spin resonance inchlorophyll-containing plant material. Proc Natl Acad Sci USA43: 387–393

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