Doing crystal diffraction without the crystals

A simple X-ray diffraction pattern. Proteins make many, many more bright spots.

UCSD

The (relatively) ancient art of crystallography has had a huge impact on modern science by showing us the location of atoms within a molecule. The structure of DNA (and how it acts as an information carrier) was worked out in part by using crystallography. The first step to understanding how a protein functions is often to figure out its structure using—you guessed it—crystallography. But despite its impact, crystallography feels a bit like an old-fashioned dark art.

To get a meaningful X-ray scattering pattern, the sample has to be crystallized in significant amounts. Without this, no structure can be determined (and crystallography really would be a dark art, in the sense of not producing any data). Crystallizing materials can be very difficult; obtaining crystals of rare, naturally occurring compounds is even more difficult. Much of X-ray crystallography is therefore devoted to coaxing recalcitrant molecules to align in regular patterns.

When a Japanese group of researchers reported X-ray crystallography without crystals, I couldn't resist delving in, even if we are a couple months late to the party.