Photosynthesis Research 34: 323-325, 1992. © 1992 Kluwer Academic Publishers. Printed in the Netherlands.

Robert ('Robin') Hill: An appreciation Martin D. Kamen

Professor Emeritus, University of California, Santa Barbara, CA 93108, USA Received 13 January 1992; accepted 18 February 1992

Cambridge is many things to many people, but to those engaged with research in oxygenic photosynthesis it was the place where Robin Hill worked and where Robin and Priscilla Hill lived. Stated simply, Robin was an authentic genius and polymath. Priscilla was a worthy companion who provided the security and stability Robin needed to forge his great scientific career over so many decades at Cambridge. (He missed his 92nd birthday by only a few days.) It would be fatuous to attempt an evaluation of Robin's scientific achievements in a short format. In any case, there is exhaustive documentation to attest to his stature. The existence of this volume provides added testimony. Briefly, Robin, more than any single investigator in this century, was responsible for bringing research on the mechanism of the photosynthetic process in green plants into the mainstream of m o d e r n biochemistry. In his great classic paper on the chloroplast (Hill) reaction, he demonstrated that the partial reactions of oxygenic photosynthesis could be observed and studied in cell-free extracts of plant leaves. He showed decisively that the evolution of oxygen could be uncoupled from the reduction of carbon dioxide. Later he elaborated, with Fay Bendall, the socalled Z scheme which described oxygenic photosynthesis as composed of two systems, Photosystem I, which concerned production of cell material from CO_~ and Photosystem II, which involved the liberation of oxygen. These proposals provide the present basis for further research on this supremely important natural process. Robin's biochemical powers were not confined to the study of photosynthesis. One may recall a pioneering paper on the reconstitution of haemoglobin in which he showed that a catalytic entity

could be dissociated into constituent prosthetic haem and apoprotein, and then recombined to produce the original haemoglobin with all its catalytic functions intact. A similar experiment on the old yellow enzyme at about the same time was instrumental in the award of a Nobel Prize to A. H. Theorell. Robin proposed prophetically in his classic paper on the chloroplast reaction that proteins analogous to those active in respiration (e.g. cytochromes) could function in the photosynthesis process. This was the basis for my collaboration with Robin when I first came to Cambridge in the mid-fifties. Robin and his associates, Davenport and Scarisbrick, had shown the presence of such a protein in chloroplasts and had isolated and purified it from its bound form (so-called 'cytochrome f'). In our laboratory, Vernon and I had found cytochromes in the bacterial chromatophores which carried out anoxygenic photosynthesis. Thus, Robin's proposal was seen to have general validity. However, one of the haem proteins we had isolated seemed to possess such anomalous properties that it seemed mandatory to show it to Robin and to have the advantage both of his remarkable insights as a master systematist and of his skills as an organic chemist. When I arrived with several grams of a purified preparation, Robin immediately arranged a session in the laboratory of David Keilin, the master cytochromologist. We spent a memorable afternoon under Keilin's guidance and Robin's monitoring, examining the results of innumerable ligand binding reactions, with the Master crouched over his famous hand spectroscope reviewing the tubes of reactants we handed him. It was with some satisfaction for me that Keilin pronounced the protein as an authentic form of haem com-

324 pound with properties he had not expected might exist. Both Robin and Keilin assured me the protein (later the prototype for a class of haem proteins termed 'cytochrome c") was, in all probability, not an artifact of preparation but worthy of continued intensive investigation. It was this reassurance that helped sustain later many decades of research on bacterial cytochromes. It should be noted that Robin, from the fifties on, had stressed continuously that proteins found in mitochondria and chloroplasts formed electron-transfer chains remarkably similar in structure and composition. The same was found to be true for the chromatophores of photosynthetic bacteria. In the later Z scheme this type of chain connected the two photosystems. In the chromatophores it functioned in a manner similar to those in chloroplasts and mitochondria - namely, passage of electrons through the chain could be coupled to phosphorylation of nucleoside phosphates, so that one could begin to understand the mystery of how photochemical free energy, or oxidative free energy, could be transduced to useful biochemical free energy as ATP. From the beginning of our collaboration, Robin realized that my background, botanical and herbal, was nil. He set himself to remedy these deficiencies. One of his devices was to take me for many guided tours through his fabulous garden with its many specialized greenhouses. I remember the awe I felt when he showed me authentic samples of woad, from the leaves of which one could express, merely by rubbing, the blue pigment I had read ancient Picts used to anoint their naked bodies before rushing into battle, and which had been official issue of the British navy in the previous century. Another device was to formulate research projects which not only suggested themselves for research on haem proteins, but also might flesh out my background of botanical lore. An example is provided by what may be called the Orache Affair. Orache (of the genus 'Atriplex') is a plant with many varieties, similar to spinach (in fact, one of its varieties was known as mountain spinach) which was in common cultivation up to the beginning of this century, after which farmers no longer raised it. From its description, Robin

determined that its leaves might be good starting material for chloroplast preparations. However, he could find no seeds available anywhere in the United Kingdom. As I was directing research in a section of the C.N.R.S. (French) Laboratory of Photosynthesis of Gif-sur-Yvette, he suggested that through my contacts there, I might find a source of Orache seeds. Filled with enthusiasm at the prospect of helping Robin in a botanical way, I threw myself into the search and, thanks to help from my staff at Gif, I found that the French knew Orache as 'Arroche'. (Apparently a transposition of vowels had occurred crossing the Channel.) Armed with this knowledge, I haunted the streets of the seed sellers and garden supplies in Paris, but to no avail until I happened to wander down a side street and noticed a small shop which seemed to specialize in exotic plants. By then I had acquired a substantial store of knowledge about Atriplex and its relatives in the course of this search, which of course Robin had expected. The store featured a wall made up of little boxes in which resided packets of plant seeds in astonishing varieties. The little old lady who ran the shop remembered vaguely having seen Arroche seeds at some previous time. After some fumbling she found a box in which there reposed a single packet of Arroche seeds. The variety (called 'brown') did not seem to tally with those mentioned by Robin, but there was no doubt from the picture on the front of the packet that these were authentic Arroche seeds. Triumphantly, I bore the packet back to Cambridge where Robin, expressing delight and some amazement at my success, took the seeds, found them viable and raised enough plants to make his preparations. It developed that while the chloroplasts produced had good activity, they were not so spectacular as to warrant continued maintenance. However, I had learned much about a number of plant genera. As the years passed, my wife Virginia and I became regular visitors to the Hill establishment, a rambling spacious manse, known in olden times as Vatches Farm, situated in Barton on the outskirts of Cambridge. A typical day began with all of us meeting at some reasonable hour in the early morning for a breakfast-tea collation, after which Robin and I set out for a somewhat jolting

325 journey to the laboratory on Old Tennis Court Road in Cambridge. Arriving there, we began an intensive morning labor. To a casual visitor the laboratory might present an aspect of chaos, but such an impression would not be accurate. Robin knew what was in the laboratory, where it was, and why it was there. Often, I ascertained this by inquiring about obtaining a certain compound which was not mentioned in any of the drug and chemical supply house catalogues. Unerringly, having made the typical gesture of moving his spectacles high up on his forehead, Robin would proceed to a particular heap of small bottles that lay jumbled on a bench and produced from the pile a vial containing the compound in question. There were dozens of such preparations lying in casual disarray around the laboratory, products of Robin's skill in synthetic organic chemistry. He had made these compounds at various times either as candidates for Hill reagents (H-acceptors for the chloroplast reaction) or just to satisfy his aesthetic urges (he was an excellent water colorist). As the noon hour approached, we called a halt to the work and discussed the pleasant prospect of a visit to some nearby pub for a lunch of the delicious crusty sandwiches and warm ale particularly enjoyable in Cambridge. This could also provide the occasion for a Happening. As an example, I once mentioned I had a check to deposit in a bank downtown where upon Robin remembered he, too, had such business to transact (he had been carrying a check Priscilla had given him to deposit for sometime) and he inquired whether he might accompany me. One of his charming traits was always to ask permission to do something he expected to do in any case. Arriving at the bank, we chanced on Kendrew, then occupied with his attempt, eventually successful, to decode the structure of myoglobin from analysis of X-ray diffraction data. Seeing Robin, he was reminded that he had for some months been intending to brace Robin on the possibility of reconstituting a myoglobin with a prosthetic haem group containing a heavy metal like gold in place of the iron. Such a molecule could be useful in solving the ever-present phase problem. In the midst of the ensueing discussion, I wondered if anyone had seen Perutz, where-

upon a lady standing some 20 feet away in a line at the counter turned and remarked that he had returned to Cambridge the previous day. Who she was and how she knew this it occurred to no one to ask, as such a random bit of information retrieval was not considered remarkable in Cambridge. Returning to the lab we worked on to the tea hour when we stopped to join our various colleagues and coworkers in the Biochemistry Department for a period of animated discussion. Often some biochemist notable was present as a visitor. It may have been at one of these sessions that Robin introduced me to Richard Ambler, then a graduate student in Fred Sanger's laboratory, with whom I began a fruitful collaboration which over the next quarter century provided the basic data for the comparative biochemistry of cytochromes c. It was then back to the Farm where preparations were underway for the evening's bountiful repast. Priscilla and Virginia had gathered fresh vegetables from the garden. Often the ritual of grinding the pungent horseradish was left for Robin and whoever else would volunteer. The procedure always produced much lachrymation and a good start for a preparation of lysozyme. Before starting dinner we always had a short period of relaxation featuring the imbibing of various aperitifs and liqueurs concocted and presented with shy pride by Robin. Dinner was always a special occasion, sometimes graced by the presence of illustrious guests, like the Needhams. Frequently, dinner would be followed by an excellent evening of chamber music, presided over by Priscilla, an accomplished amateur cellist who had recruited competent musicians, both amateur and professional, with which Cambridge teemed. One may perceive from this brief narration the special way the Hills added to the totality of the Cambridge experience. Now that there is no longer the presence of Robin and the Happenings he inspired, a euphoric component of the Cambridge ambiance has been lost for all of us who enjoyed the privilege of living within the Hill orbit. What is left are the memories and a sadness born of deprivation to which we eventually will become resigned, but never wholly reconciled.

Robert ('Robin') Hill: An appreciation.

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