Raymond Gosling: Flickr set dedicated to PhD thesis, 'X-ray diffraction studies of Deoxyribose Nucleic Acid '

Following the successful digitisation of Raymond Gosling's PhD thesis, 'X-ray diffraction studies of Deoxyribose Nucleic Acid' I have added a few of the images onto the project’s Flickr site: http://www.flickr.com/photos/51665752@N04/sets/72157631533614623/ .

(KDBP/5/1)

As I have already stated in the previous posts, Gosling was a vital worker in the King's effort to solve the structure of DNA. His PhD provides an excellent record of the experimental work going on at King’s - not only in terms of x-ray diffraction crystallography on the Signer DNA but the initial diffraction studies on sperm heads; the microscope-based work occurring simultaneously on nucleic acids and descriptions of model building, theoretic analysis of data and apparatus design are also described.

(KDBP/5/1)

The source, from an archival perspective, is ‘visually exciting’. Scientific records tend to be fairly cryptic with significance often hidden within the text or captured in a graph or table. The photographic prints within the thesis give a clear linear progression of the diffraction pattern that were being obtained at King’s. Broadly speaking, it is possible to see the improvement of images as the old x-ray equipment was discarded for the finer focus camera and x-ray tube and the presence of an expert crystallographer, in the form of Rosalind Franklin at the helm. 

Front cover of Raymond Gosling's PhD thesis (KDBP/5/1)

You can now access for free Raymond Gosling's thesis, via the Wellcome Digital Library- here. You can also search for other digital material relating to Raymond Gosling and other King's DNA workers via the Wellcome Library catalogue, as well as access collections from other archives relating to the history of modern genetics. 

Raymond Gosling: Not just an extraordinary envoy

Raymond Gosling was one of the key workers on DNA at King's during the period that became immortalised as the 'Race for the Double Helix'. His achievements have been eclipsed by the personality clash between Rosalind Franklin and Maurice Wilkins.  Gosling’s own role as the rift developed became that of "an Envoy Extraordinary and diplomatically carrying the "sense" of messages between them".  However, there was much more to Gosling's role than acting as a courier between the two parties and the next three posts will be dedicated to his role at King's. 

In the papers of Maurice Wilkins and those of the department of Biophysics Department are correspondence, articles, a PhD thesis, photographs and the diffraction patterns that Gosling produced with both Wilkins and Franklin. All these images have been selected for digitisation and this post contains a few samples of the type of material the collection holds. 

 One of our oldest pieces is a postcard sent to Wilkins from Gosling while on his honeymoon in 1950. His honeymoon consisted of touring Italy on his motorbike. Recently, I discovered that Wilkins, too, used to get lifts on the back of his motorbike after late nights working on x-ray diffraction experiments in the summer of 1950. Wilkins described this as “rather scary” but “enjoyed his hilarious time together” with Gosling. 

(ref: K/PP178/3/12)

(K/PP178/3/12)

The experimental biophysics work that King's has become known for in the solving of the structure of DNA was X-ray diffraction and Gosling's importance is undisputed. Gosling was the first to apply x-ray diffraction techniques on nucleic material at King's with the study of ram sperm heads in 1950. Later that year Gosling moved on to looking at DNA specimens and Wilkins brought him the calf thymus DNA donated by Rudolf Signer. The two began to collaborate and managed through innovation and some luck to produce a crystalline multi-fibre diffraction pattern of DNA that proved to be the breakthrough required to show that the structure of DNA was a feasible proposition. Soon afterwards new equipment and an expert crystallographer, in the shape of Rosalind Franklin, were brought in and Gosling was handed over to be Franklin's assistant. Gosling and Franklin made great strides and soon discovered through Franklin's control of the humidity levels that DNA occurred in two phases, called Structure A and B, and that this change could be reversible. This observation was followed up with further deductions based on the effect of water content on both structures. Whilst the rift within the lab affected joint efforts, Gosling and Franklin did go on to produce a three dimensional Patterson function of Structure A DNA, the data from which helped to prove the correctness of the Watson-Crick model.

Early calf thymus x-ray diffraction pattern produced by Raymond Gosling, 1950 (ref: K/PP178/5/1/1 Copyright: King's College London)

X-ray diffraction patterns of Structure A and B from Franklin & Gosling's article in Acta  Crystallographica, ' The  Structure  of  Sodium   Thymonucleate  Fibres. I.
The  Influence  of Water  Content', 1953 (ref: K/PP178/2/28 copyright: Please contact King's College London Archive Service)

  In the late 1970s, at the request of Wilkins, Gosling produced a recollection of his time at King's to allow Wilkins to reconstruct a popular account of DNA work at King's to counteract claims made by the recently published biography of Rosalind Franklin, by Anne Sayre (1975).

Some Recollections of DNA Studies in the Biophysics Laboratories at King's College. (ref: KPP178/5/6)

He described the atmosphere at King's as "friendly and positive". The interdisciplinary subject of biophysics was excitingly innovative and Gosling describes being 'exhilarated' by the prospect of investigating the 'dynamics of the single cell'

Some Recollections of DNA Studies in the Biophysics Laboratories at King's College.(ref: KPP178/5/6)

For Gosling, this period at King's could be broken down into four stages: firstly, the preliminary work around DNA before x-ray diffraction studies began and culminated in the first good crystalline pattern; secondly, the arrival of Franklin and the observation of two phases , Structure A and B, in DNA; thirdly, the interpretation of water content within the specimen and finally the ‘schism’ between Franklin and Wilkins.  

 In his concluding remarks, Gosling notes that it was his belief that Franklin never wholeheartedly believed that the structure was other than helical, despite giving that impression to Wilkins and Stokes. Perhaps the most telling observation is the following:

"If only Rosalind and Maurice had not been such shy people they might have been able to cooperate well in spite of their different views on how to set about solving the structure of DNA". 

You can read the full account of Raymond Gosling's reflections on his DNA work at King's via the Wellcome Digital Library- here. 

Objectifying DNA

  The artefacts within the combined papers of the Maurice Wilkins and Biophysics collection include some of the most striking items in our holdings. Correspondence may have warmth and wit and the experimental notebooks may actually give the how and why but nothing beats the sheer visual punch of the DNA wire model or a X-ray diffraction camera. The artefacts are all the more impressive due to the diversity that the collection holds. Highlights include: original DNA fibres supplied by the Swiss biochemist, Rudolf Signer, which were the main source of DNA used in the X-ray diffraction experiments by Rosalind Franklin and Raymond Gosling; several X-ray diffraction cameras including the micro camera used to obtain "Photo 51", the picture of B structure DNA that so sharply showed a helical structure of DNA; DNA models and diagrams that the Biophysics Unit used to construct and refine more detailed models of DNA, with the pride and joy being the several metre long roll of the DNA molecular model ceremoniously nicknamed the "DNA toilet paper". These are a few of our favourite things and they are joined by many other items that directly relate to DNA and previous microscopic research carried out on the subject.

A few of the DNA related artefacts at King's Archives such as the single fibre X-ray camera used by Rosalind Franklin, glass vials containing original DNA samples used in the X-ray diffraction experiments, DNA diagram and Biophysics photo index

The collection has a remarkable degree of preserved DNA samples from the 1950s that not only include the Rudolf Signer Calf Thymus DNA that produced excellent B configuration X ray patterns sample but also DNA samples prepared from other scientists such as Erwin Chargaff and Leonard Hamilton which used a variety of other DNA sources like bacterial cultures and human DNA.

"Dear M": the transatlantic DNA collaboration of Maurice Wilkins and Leonard Hamilton

This week's post calls attention to a series of correspondence written in the 1950s that documents the DNA research carried by Wilkins and his group at King's College London from 1953 to1960. The correspondence is with Dr Leonard D Hamilton, a British medical researcher and pathologist based in the United States who worked for the Sloan Kettering Institute for Cancer Research and later the Brookhaven National Laboratory. He provided DNA samples to Wilkins at King's from 1952 into the 1960s. As my title suggests the two were firm friends and their letters are refreshingly candid. Although these letters do not document the breakthrough research on the structure of the double helix like the similar correspondence between Wilkins and Crick they do give us a good picture of how Wilkins coped with the news and life thereafter.


DNA Samples: Supply and Demand

In 1953, Leonard Hamilton became the principal provider of DNA for the King's team. Samples had previously been provided by a host of other international scientists such as Rudolf Signer, Erwin Chargaff and Harriet Ephrussi and there was a great pressure to produce better DNA samples now it had been established that DNA was the basis of genes.Wilkins and his team were also under pressure to provide a more detailed double helical model to confirm that the structure was correct and not an equally valid alternative structure.

Figure 1: Photocopy of a letter from Wilkins to Hamilton, dated 28 May 1953: Wilkins thanks Hamilton for the DNA sample taken from a mouse sarcoma and generally expresses an eagerness to press on with further DNA research.

 In the above letter, Wilkins shows his excitement over the diffraction image obtained using the S-180 mouse sarcoma sample. He also expresses the need for greater quantities and variant salts and solutions that becomes a constant theme of this correspondence, as this quotation from a letter from Wilkins on the 9 June 1954 reveals:

"As I thought I made clear, what we need is better DNAs and hence I was very disappointed to find all the samples you sent recently were no better than the usual quality. We have not the time to test laboriously numerous samples in the hope one might be good. The three dry samples were have had already and those in solution, owning to a lack of warning, arrived at this end and were held at the airport for several days and appear to have deteriorated". 

The problem of the supply of demand of DNA were exacerbated by the trans-Atlantic nature of the partnership. Communication was the biggest issue. Before the days of global mass-communication, the main medium for communication was by letter or telegram (international telephone calls had only recently been introduced and were very expensive). The frustration was felt on both sides of the Atlantic especially with the additional pressures of journal and conference deadlines. Despite these stresses, they made progress as this quote from Wilkins on 5 November 1954 states:

"The 10 week exposure came off today and is a great success. it is one of the biggest improvements we have ever had in A pictures and is very much better than the best before. Will send a copy soon and I hope I will spur you on to even better things...Good old Leonard!"

Living in the Shadow of the Watson-Crick Model

One of the reasons why these letters make compelling reading is the scattered references to the discovery of the Double Helix. In the letters we get a contemporary commentary on the initial impact of the discovery and personal opinions on some of the key characters such as Francis Crick, James Watson and Rosalind Franklin. Of particular interest is the response of Hamilton who considered that Wilkins and King's College London Biophysics Unit had been hard done by Watson and Crick's model.

Figure 2: Letter from Leonard Hamilton to Wilkins dated October 12 1954: In this letter, Hamilton describes a visit from Rosalind Franklin and also his plan to air off a little "pro-Wilkins propaganda!" at a nucleic acids conference. 

 From the correspondence, it is clear that the battles and wounds caused by the discovery are still fresh but the scientific interest in the findings ( such as the journal Scientific American in Figure 2) are already calling for a narrative of the discovery. Hamilton's repeated opposition to calling the double helix the Watson-Crick model is an example of this increasing scientific interest and his own attempts to inform the American scientific community of the role that King's Biophysics Unit played in its creation. 

Wilkins' own initial thoughts and feelings were somewhat more ambigious. For example, his assessment of Francis Crick in the letter shown in Figure 1 states:

"Taken the Watson Crick model with a grain of salt. Francis is quite certain he can solve all the problems of the universe by pure thought and his lack of facts had lost him many friends temporarily until he recovers from DNA hysteria. I am very fond of Francis but he can be a bit much at times and he can be a ruthless careerist when he thinks it suits him. but keep that quiet to ourselves. We both like him a lot so there is no harm saying this to you".

His reaction is in line with his famous letter to Crick on hearing the discovery where he called Crick and Watson a couple of "old rogues" but accepted the model gracefully. Yet in this letter he does admit a degree of resentment over the Crick's "careerist" tendencies but not enough to irreprecibly damage their friendship. 


Finals thoughts

The correspondence between these two friends is of great reading for anyone interested in the story of the double helix and the DNA research carried out at King's College London. By being both a commentary and account of the DNA research undertaken at King's in the fifties the letters acts as an informal guide to the work being carried out and excellent source of information of the different DNA salts and samples. For me, however, the best aspect of the letters is the openess and informality that Wilkins shares with his friend about his life and research.  

Figure 3: Leonard Hamilton and Maurice Wilkins together in the 1960s.

Final words

"Do please reply soon. The nature of the gene depends on it. What piffle. M"

Short and Simple (ish) Guide to X-ray Diffraction

  X-ray diffraction (or X-ray crystallography) was the chief physical method used to determine the structure of DNA. In this post, I will briefly and as simply as I can (which with my non-scientific background should not be a problem!) explain what x-ray diffraction technique is and its relative importance to the overall discovery.

What does X-ray diffraction actually mean?

 X-ray diffraction is the method of projecting a beam of X-ray radiation at a target object and through to a photographic film on the far side. A series of spots appear on the photographic film following this exposure, which is formed by the x-ray radiation diffracting off the structure that they passed through. These diffraction patterns give an indication of the general structure of the object (such as an inorganic crystal or macro- molecule such as DNA) which can then be delineated using complex mathematical formulas.

Why use X-rays in the first place?

The reason why X-ray beam is required in the first place is that atoms are too small (0.1nm between them, bearing in mind that 1 millimetre = 1000000 nanometres) to be revealed using visible light and therefore could not be viewed by a light microscope (even an electron microscope does not possess the required magnification). X-ray radiation fits the appropriate wavelength to be diffracted by the object and produce visible results.   

What causes the diffraction of the X-ray beams?

What the X-ray beam are diffracting is not the entire atom but the orbiting electrons (one of the component parts of an atom) that are close enough to the core (nucleus) of the atom to give a good indication of the structure of the unit cell (the term used for the repeating unit found in crystals and macromolecules). The end image is known as an electron density map of that unit cell. However due to the incredibly weak image a single molecule would produce, a crystalline structure is used instead, for example common salt (NaCl), since a crystalline structure provides a huge number of molecules arranged in the same orientation and therefore produces the same scattering effect on the X-ray beams. 

In this diagram, the diffraction of the X-ray beam causes an image with a helical arrangement to form as all the DNA molecules in a fibre are aligned in the same direction.

X-ray diffraction of nucleic acids at King’s College London from 1950 to 1953 

 X-ray diffraction studies on DNA began in June 1950 when Maurice Wilkins asked PhD student Raymond Gosling to assist him in diffracting the DNA fibre samples prepared by the Swiss biochemist, Rudolf Signer. Fibre diffraction did not usually provide good quality images because of the thinness of the fibres and therefore a very small mass to scatter the radiation. Nevertheless, the fibres’ remarkable uniformity when wetted allowed Wilkins to manipulate them into a bundle and mount them on a wire frame to obtain x-ray diffraction images. The initial images showed promise but Wilkins and Gosling were greatly assisted by J T Randall’s own experience with X-ray diffraction.  He advised how the surrounding air could affect the x-ray scattering. The solution was to pass hydrogen through the camera and control the relative humidity of the sample.  With this in place, the resulting images were much sharper and showed a clear crystalline diffraction pattern.

X-ray diffraction pattern obtained by M H F Wilkins and R Gosling in late 1950 showing a clear crystalline arrangement.

It was in late 1950 that the theoretical physicist Alec Stokes first noticed an interesting observation from the images. He realised that there was no diffraction at all along the length of the molecules: a sign that DNA might be helical.  However, the King’s College team needed far sharper images to confirm this hypothesis. This required a new X-ray camera that could work on single fibres.  Through a fortunate coincidence, Werner Ehrenberg and W E Spears had just developed one at Birkbeck: this was generously loaned to the King’s College team.

Before the new camera was set up, it was decided that Rosalind Franklin, who was joining the laboratory from Paris, would replace Wilkins in producing the x-ray diffraction images with the continued assistance of Raymond Gosling. Both Stokes and Wilkins continued working on the problem with the latter embarking on some rough tests with the old X-ray diffraction camera on various DNA specimens that produced an observed “X” crossed pattern. The X pattern of diffraction was created by the x-ray radiation scattering at right angles off the "zigzag" structure of the DNA chain.  This interpretation was further supported when Franklin and Gosling produced the first “B” structure X-ray patterns in the late summer of 1951. This was a crucial development as it showed two observed states of DNA: crystalline “A” and semi-crystalline “B” (the best B structure diffraction photograph became known as “Photo 51”). The photos also supported the predicted observed readings of a helix that Alec Stokes had developed using the mathematical technique known as Bessel functions.

Plot of Bessel Functions for a smooth helix, named "Waves at Bessel-on-sea" by Alec Stokes who completed the calculations for the diagram over a single train journey.

It was now Maurice Wilkins and Rosalind Franklin disagreed over the direction of the research in finding the overall structure. Wilkins was keen on hypothetical model building while Franklin favoured a more systematic study of the structure. This parting of ways can be partially explained as stemming from the limitations of the x-ray diffraction process itself. For example, the evidence from the photos clearly pointed to a helical structure but this begged question: what type of helix? Helices in nature could occur in single, double and even triple strands and there was no clear indication, which was the right number. This is why the King’s College London attempt at model building proved to be a failure when the model made by Bruce Fraser showed a triple helix based on the chemical readings but was unable to fit with the rest of the x-ray data. A crucial piece of the puzzle was missing and related closely to DNA’s function of providing the genetic material for life: it was only when Jim Watson and Francis Crick came up with the base pair hypothesis that the double helix seemed the ideal form. 

In this diagram, we can see the general similarity between a single and a double helix.

X-ray diffraction studies undertaken at King's College London provided part of the experimental structural data needed to solve the general structure of the DNA double helix. Yet, as important as these observations were other methods and disciplines were of equal importance in unravelling the overall structure, in particular the biochemical work of Erwin Chargaff and the biological insight of Jim Watson. X-ray diffraction work on DNA at King’s did not finish with the unveiling of the structure in March 1953 but continued for another decade as Wilkins and his team worked to test to the correctness of the "Watson-Crick" model. 

A potted account of the research on DNA at King's College London

In this post, there will be a brief overview of the research carried out here at King's on the structure of DNA. This of course is not a definitive history of the events and interactions which led to the discovery of a double helix. For a more comprehensive scientific history of DNA, I would recommend Robert Olby's book "The Path to the Double Helix: The Discovery of DNA" (1974). My purpose is to introduce some of the techniques and findings that occurred here at King's and relate it to the overall contribution to identifying the structure of DNA.

DNA enters the 'Circus'

The new Biophysics Laboratory created by J T Randall at King's College London was a lively and unconventional institution. Randall's ambition to create a laboratory where physicists could work on biological problems and vice versa were being realised at King's and an assortment of young research workers from diverse scientific backgrounds found their feet in these new disciplines. Maurice Wilkins was one of these workers. His first years at King's had proved fruitless in the field of ultrasonics causing mutations in fruit flies and he swiftly moved on to construct, with his colleagues Bill Seeds and K P Norris reflecting achromatic microscopes which he began to use on ultraviolet and dichroism studies on the Tobacco Mosaic Virus (TMV), nucleic acids and nucleoproteins. During these initial experiments with DNA Wilkins found a significant finding he wrote in 1962:

"While examining oriented films of DNA prepared for ultraviolet dichroism studies, I saw in the polarizing microscope extremely uniform fibres getting clear extinction between crossed nicols...each time that I touched the gel with a glass rod and removed the rod, a thin and almost invisible fibre of DNA was drawn out like a filament of spider's web. The perfection and uniformity of the fibres suggested that the molecules in them were regularly arranged"

Polarising microscope view of DNA fibre stretched at room humidity

The excellent quality of this extracted DNA was not through chance. The sample was supplied by Rudolph Signer, a Swiss biochemist who had been since the 1930s endeavouring to produce high quality extracted DNA. The sample made in 1949 with his student H Schwander made that grade. On the 12 May 1950, Signer was invited to the Faraday Society in Cambridge to discuss his work on preparing DNA samples. At the end of the talk he distributed bottles of his best DNA and Maurice Wilkins was one of the lucky recipients. Wilkins later reflected that this was "a generous act in the best tradition of science!".

Having witnessed the remarkable uniformity of the fibres, Wilkins took the DNA fibres to Raymond Gosling for X-ray diffraction. Gosling was the only person using X-ray diffraction techniques at the time to complement Randall's interest in the X-ray study of ram's sperm heads. Initially the two were unsuccessful  the specimen to the film distance too large and the X-ray tube too weak to yield a pattern but they improvised as Raymond Gosling explains:

"I wound these fibres around a wire frame, forming a dense bundle which on the conventional Raymax tube produced a diffraction pattern recordable in a few hours. If that sounds rather scientific, I must tell you that the 'wire frame' was simply a bent paper clip and the 'dense bundle' was formed by applying Lepages quick setting cement, purchased from Woolworth's in the Strand!"

First multifibre specimen taken on the Raymax tube Unicam Camera, filled with hydrogen (1950)

The above photograph is the one that Maurice Wilkins showed at the Naples conference that so captivated Jim Watson. This was obtained thanks to a suggestion by Randall , by passing hydrogen thought the camera and sealing it where possible to prevent air scattering, which caused a fog on the film. From these images it was possible to demonstrate that the molecule was packed together like cylinders 2.0 nm in diameter and  that the structure was very crystalline. The final study in this initial period was experimenting with the water content of the molecule. By drying and heating the specimen they obtained an amorphous scatter pattern .This contrasted when they repeated the process but wetted the hydrogen at 90% humidity for 12 hours prior to exposure and obtained a crystalline pattern similar tp the example above. This demonstrated that water played a vital role in maintaining an ordered crystalline structure.

X-ray Diffraction Years

In June 1950, the old wartime Siemens X-ray tube broke down leaving the department without a working X-ray diffraction camera. They soon obtained designs for new fine-focus X-ray equipment produced by Ehrenberg and Spear at Birkbeck College. Whilst the camera was being constructed Randall came to the decision that they needed a professional crystallographer to keep the work progressing. Rosalind Franklin was already on her way to the department as a research fellow to work on proteins but Randall expressed in a letter the change in orientation. The letter stated that "as far as the experimental X-ray effort is concerned there will be at the moment only yourself and Gosling..." and  gave no indication of Wilkins' continued involvement on the project. This may account for the grievance that Franklin held from what she viewed as Wilkins interpreting her problem but this issue is in no way definitive and has been heatedly debated along with the wider recognition of Franklin's role ever since. Yet, it is best to leave the issue of Franklin and Wilkins relationship to one side for a moment and recount for what was actually achieved when she joined the department.

One of the first achievements of this collaborations was a vital one in solving the structure of DNA. Franklin brought her expertise to the job by fixing the humidity and the water content of the exposures by passing the hydrogen through saturated aqueous solutions of appropriate compounds through which the hydrogen could bubble into the camera at any given temperature. They soon found that the sodium salt of DNA supplied by Signer could transform into two forms, Structure A and Structure B.

Soon after this discovery, the division between the DNA workers at King's was cemented with Franklin and Gosling continuing to work with the fine focus X-ray tube using Signer DNA to outline the Structure A pattern of DNA whilst Wilkins and Alex Stokes used the old Raymax camera and work on the Structure B pattern using Erwin Chargaff's DNA samples. This situation did not change until Franklin left King's College London in February 1953 with virtually no communication between the two groups.

In October 1951 Wilkins, who had been reading Linus Pauling's famous paper on the protein alpha-helix , wondered why Pauling had not calculated the X-ray diffraction of the structure. After discussing the matter with Stokes he came back the next day with a Bessel function calculation of diffraction of a helix. The remarkable aspect of the 'Waves at Bessel on Sea' diagram was how much it corresponded to the new B diffraction patterns that Franklin was achieving. Franklin reacted furiously to her results being interpreted and the matter was set aside.

The following month November 1951, saw the unveiling of two DNA models: one by Bruce Fraser at King's and the other by Jim Watson and Francis Crick in Cambridge. Both these models were three chained helixes and lacked the key base-pair element. Fraser's model (as described in a previous post) was a closer approximation of the correct version as a fundamental flaw in the first Cambridge model was that the helix was inside out with the bases on the outside due to Watson misjudging the water content. The failure of the Cambridge model put a temporary injunction on the pairs DNA interest, whilst model building was not pursued at King's College London after Fraser left the department shortly after this. 

At the start of 1952, Franklin, taking the advice of a Paris mentor, Vittorio Luzzati , decided to elucidate the structure of the A pattern using the crystallographic method of cylindrical Patterson function. This laborious method was a way of calculating the Fourier transform of the intensities of the spots on the X-ray films ,and involved measuring different reflexions of the specimen which required a new tilting microcamera to be designed for this process. In order to calculate the Fourier transform, Franklin and Gosling had to consult Beavers and Lipson strips (pictured below). Ray Gosling recalled that:

"These assembled the values of the periodic functions all set out at appropriate intervals and arranged sequentially in a handsomely polished mahogany box. I used to have nightmares...that I had dropped a box of 'strips' on the floor and had to sort them all out in the correct order!"

By the end of 1952, Franklin and Gosling had the preliminary results back for the cylindrical Patterson function of Structure A. Although in hindsight the data from the cylindrical Patterson and then the 3-dimensional Patterson analysis supported a double helix in the A form such a conclusion was not reached by Franklin who before leaving for Birkbeck College had begun to investigate the B form of DNA (with which, as shown in her notebooks, she would come close to solving the structure with). 

The solution to the structure:

On the 7th March 1953, James Watson and Francis Crick finished the model of the double helix. The Cambridge pair started model building again after Watson was inspired on account of being shown 'Photo 51' by Wilkins when he visited King's on the 30th January. Watson deduced that a double helix rather than a triple helix fitted with genetic transference and was supported by the biochemical work of Erwin Chargaff who had discovered that the quantities of the base pairs were equal. On the 12th March 1953 the King's team were invited up to view the model. Wilkins wrote of seeing the model: 

"...a feeling came through to me that the model, though only bits of wire on a lab bench, had a special life of its own. It seemed like an incredible new-born baby that spoke for itself, saying 'I don't care what you think - I know I am right' "

                                                              

 The diagram above on the left hand side shows some of the essential features of the double helix from the original paper by Watson and Crick such as the two sugar-phosphate chains running in opposite directions linked together by hydrogen bonded base-pairs stacked on top of each other. The diagram on the right shows a wire-model of the double helix used by Watson and Crick in their representation of the original double helical model of DNA.                     

Conclusion:

The contribution of the the Biophysics department at King's to the discovery of the structure of DNA was vital. The x-ray diffraction studies and other experimental methods provided the essential properties for Watson and Crick to elucidate the structure.Yet these achievements were not in isolation and needed to be combined with the knowledge acquired from Pauling and Chargaff along with many others to lead to the structure of DNA. The cracking of the structure should not be seen in terms of a race but the culmination of advances in chemistry, biology and physics spanning back to the nineteenth century when Fritz Miescher extracted DNA for the first time. 

Fortieth Anniversary of the Discovery of the structure of DNA. Pictured from left to right are four of the five named workers featured on the commemorative plaque (exception being Rosalind Franklin) they are: Ray Gosling, Herbert Wilson, Maurice Wilkins and Alec Stokes.

                                    

Public unveiling of frieze celebrating Rosalind Franklin and Maurice Wilkins work at King's College London

On the 13th September 2010 Principal Professor Rick Trainor unveiled the newly designed DNA frieze outside the Franklin-Wilkins building on the Waterloo Campus. The new permanent window display was sponsored by Ecovert FM to mark the 10th anniversary of the Public Private Partnership (PPP) contract with King's.  The set of friezes depict the two scientists and the key developments associated with them that led to the solving of the structure of DNA. To celebrate the unveiling members of the Franklin and Wilkins family joined the Principal and the CEO of Ecovert Group Bruno Bodin for this special occasion.

(Left to right) Jenifer Glyn, her husband Ian, Sarah Wilkins, CEO of Ecovert Group Bruno Bodin, George Wilkins, King's Principal Professor Rick Trainor and at the front, George Wilkins' two sons.

The set of friezes on street level on Stamford Street give an excellent introduction to the DNA work undertaken at King's: for the representation of Rosalind Franklin it praises the X-ray diffraction studies that she and Ray Gosling took and couples her with her most famous creation, 'Photo 51'. It's visually arresting for the casual pedestrian or distracted student but the real treat is the detail on the friezes: the extracts and images of Franklin's notebook and a brief diagrammatic explanation of the significance of 'Photo 51'. 

Frieze panel of 'Photo 51' with explanation below. 

 Maurice Wilkins the frieze acknowledges both the work that he achieved in the early fifties and the later work verifying the Watson-Crick model. Again the frieze is a fine tribute pointing out the early X-ray diffraction work and early helical interpretations harbored by Maurice Wilkins and his collaborator Alec Stokes. 

 Alongside these panels on the story of DNA is the impressive representation of the scale and enormity of DNA through a linear outline of a section of a double helix coiled around the three revolving doors of the entrance of the Franklin-Wilkins building. The creator of the artwork, Ian Chilvers of Atelier Works, aided by Dr Roland Roberts of the Department of Medical & Molecular Genetics here at King's College, scaled up a section of DNA from the smallest human chromosome (21) by a factor of 1.1. billion and applied the design to the doors used a frosted linear vinyl. The artwork gives a visual demonstration of the complexity of our genetic make-up: In order to depict the total size of this chromosome at this scale it would involve having to stack 10 million of these doors on top of each other- making it a staggering 20,000 km high!

Model of the DNA design courtesy of Atelier Works

The project is part of a larger renovation scheme by KCL and its facilities management partner Ecovert FM to reduce the ecological impact of all campus buildings. The Franklin-Wilkins building can now harvest rainwater for cleaning and toilets, reduce energy waste through energy efficient lighting and heating systems and even convert waste into biomass. This larger project would have pleased Maurice Wilkins who was a keen advocate of alternative energy use and would appreciate that a building that shares his name was pursuing an innovative and environmentally responsible policy towards energy consumption.

Exterior of the Franklin-Wilkins building on Stamford Street