Revealing structure: X-ray crystallography
Amy Thompson revisits the technique that science has overlooked
X-ray crystallography is a fundamental method used to study atoms that make up a solid object. As the name suggests it involves the used of X-ray beams, which are fired at the solid that has been made into a crystal form. Information is received from the X-ray beams as they bounce off the crystal; this is recorded as a series of dots. These dots reveal the organisation of the atoms within the solid structure allowing scientists to see how a structure is arranged. It is a complex procedure based on highly intricate, yet fundamental mathematics that enable the prediction of a solid structure to be mapped out.
X-ray crystallography is a technique that is not given enough praise; it has been vitally important in the fields of biology and chemistry and has aided many landmark discoveries. In total, 48 Nobel Prizes have involved the use of X-ray crystallography, without the procedure the prize recipients would not have been able to produce the data needed to demonstrate their findings.
One of the most important scientific discoveries was detecting the structure of DNA. The use of X-ray crystallography by Rosalind Franklin and Maurice Wilkins in the 1950s have researchers the first glimpse into the possible structure of DNA> this work is what later inspired Watson and Crick ino their discovery of the double helix structure of DNA.
X-ray crystallography was a procedure founded and developed by the Braggs, a father and son team, and it over a century old. Despite founding X-ray crystallography, the Braggs are widely unspoken of within the scientific community.
Dorothy Hodgkin was a pioneer in X-ray crystallography. However, like the Bragg, very little is known about her work, but without her discoveries numerous scientists would never have taken the technique seriously. Hodgkin was able to develop the technique further than the Braggs, enabling greater detail of protein structures to be show by the X-ray beams. This allowed her to study the structures of some of the largest proteins during the 1950s. Hodgkin was able to identify the structures of penicillin, vitamin B12 and later insulin. Hodgkin won the Nobel Prize in Chemistry in 1964, for her discovery of the structure of vitamin B12.
The most important achievement of Hodgkin and her team was analysing the arrangement of insulin. This knowledge allowed for synthetic insulin to be developed, which is still used for current treatment for type I diabetes sufferers.
Unlike many other scientists such as Darwin, Hawking, Curie or Franklin, many households will have never heard of Dorothy Hodgkin, despite her scientific discoveries being essential in the development of insulin and in the progression of biological research.
Many scientists are “unsung heroes,” who have helped the world but have not gained fame or fortune from their discoveries. Many scientists today are like Dr Dorothy Hodgkin, they do their work in order to gain a greater understanding of the world. Hodgkin could not have imagined that her discoveries would benefit so many, which is why scientists like Hodgkin should be celebrated, not only for their discoveries, but also for their selflessness in the pursuit of scientific advancement.
The procedures involved in X-ray crystallography are fascinating, but it is an unfamiliar scientific tool of which many science students will not have heard. It is a process that allows scientists to discover new protein structures and it is used to learn more about the structures that both surround us and make is. Specific data banks, like the PDB (Protein Data Bank) are now available to all with one internet search.
The importance of X-ray crystallography was summarized best by Nobel Prize winner Max Perutz; he stated that X-ray crystallography shows “why blood is red and grass is green, why diamond is hard and wax is soft, why graphite writes on paper and silk is strong.”
From Issue 11