It’s the science behind flat-screen televisions, HIV treatments and chocolate manufacturing. Yet few nonscientists are familiar with crystallography.
That’s the problem the International Union of Crystallography wants to address with the International Year of Crystallography, which commemorates X-ray crystallography’s 100-year anniversary.
X-ray crystallography is a technique that scientists from all disciplines use to find the structure of molecules and compounds.
“If you can get (a chemical compound) into the solid state, you can usually grow a crystal of it,” said Marilyn Olmstead, professor of chemistry at UC Davis. “Once we have the crystal, we can use the technique of X-ray crystallography to determine the exact structure.”
In X-ray crystallography, a small sample of a crystal is placed in an instrument where it is bombarded with X-rays. The X-rays bounce off the electrons surrounding the atoms in the sample, overlapping and interfering with each other.
The pattern of X-rays bouncing off the sample is collected as image data. Then a computer digests the data to find the sample’s structure: the arrangement and types of atoms in the crystal’s molecules.
“Essentially, what we’re doing is collecting this image data and using that to work backwards to figure out what comprised the (molecule),” Olmstead said. “Different atoms have different responses to X-ray radiation.”
Olmstead offered an analogy: X-ray crystallography is like listening to an orchestra play.
“You have all these different instruments, and the different sounds that the different instruments make are waves — sound waves,” Olmstead said. “Your ear picks up the combination of all these (waves), but your ear and your brain are smart enough to actually work backward and figure out which instrument made which sound.
“It’s the same with crystals,” Olmstead said. “Different atoms have a different response to X-ray radiation,” like the different sounds instruments make. Computers work backwards to identify each atom based on its response to X-ray radiation, just like the human brain works backward to identify an instrument from the sounds it makes.
But why is crystallography important?
“One-eighth of all the Nobel Prizes in chemistry and physics have been awarded in crystallography,” said Martha Teeter, president of the American Crystallographic Association and a Davis resident. “It’s got enormous impact on society.”
Crystallography is behind a wide range of technological and medical advancements, with the potential for many more.
“Every single formula of every drug that’s ever been synthesized, we know the arrangement of atoms from the crystal structure,” Teeter said.
For example, Dorothy Hodgkin and her team found the structure of insulin in 1969 using X-ray crystallography. Today, these advancements allow insulin to be synthesized for the world’s 230 million diabetics, according to the International Year of Crystallography website.
DNA’s famous double helix shape also was found through X-ray diffraction, according to the International Union of Crystallography.
And in the 1960s, Hakon Hope, professor emeritus at UCD, and his team made significant advances in the science of crystallography at UCD, Olmstead said. Hope pioneered a technique for using X-ray crystallography with proteins that is now used all over the world, according to Teeter.
Crystallography research continues to be important at UCD today.
William Casey, a professor of chemistry, uses crystallography to find substances that could become the next generation of semiconductors, which are important for electronics. Louise Berben, a professor of chemistry, and her team use crystallography to hunt for catalysts that might let future scientists make fuel out of carbon dioxide and water.
Other crystallography-related projects at UCD include research on antibiotics, energy and cancer therapeutics. Even the UCD entomology department sometimes uses X-ray crystallography to find the structure of insect pheromones, Olmstead said.
UCD’s crystallography facilities are large.
“We have three instruments running most of the time,” said James Fettinger, director of the X-ray crystallographic laboratory at UCD. The laboratory analyzes close to 900 samples a year, a comparatively high number of samples, Fettinger said.
Olmstead and Fettinger want to share crystallography’s importance with the community of Davis. According to Teeter, that’s the point of the International Year.
“The International Year is to bring the awareness of crystallography to the general public,” she said. “A good way to do that is by bringing it to young scientists and families, so that’s why we’ve concentrated on schools. There are also lectures and activities at the university level.”
Olmstead and Fettinger are working on ideas for crystallography outreach for Davisites of all ages. In the past, Fettinger said, he’s made presentations at Da Vinci High School.
“(Students) like the idea of what you’re doing, but crystallography is hard to understand,” Fettinger said.
Olmstead sees crystallography as a way to impart a basic understanding of chemistry to students.
“Ultimately, you want them to have some sort of mental image of what a molecule is,” she said.
Teeter hopes to get Davis schools involved in the International Year’s crystal-growing contest for elementary and high school students.
“(The contest) ties in to the next generation of science standards, which are very experience-oriented,” Teeter said.
Teeter sees the technique of crystallography as more important now than ever.
“Our young scientists are our future of science,” she said. “We would like to use crystallography to excite young people about science. ….We have really, really hard problems today, and in order to solve them we need a lot of people trained (in science).”