Crystal Illumination

SLIPPERY MEMBRANES

While research in structural genomics is receiving a giant boost from the automated devices on the market, one sector is still stumping even the best crystallizers: membrane proteins. The vast majority of drugs target membrane proteins, such as receptors, making crystallization of membrane proteins a priority, says Martin Caffrey, a structural biologist at the University of Limerick, Ireland. Yet current crystallization methods don't work for membrane proteins that have hydrophobic membrane-embedded regions, which avoid the water that's central to the principles of vapor diffusion and microbatch.

So far, Caffrey has found that a combination of detergent, water, lipids, and protein can form a liquid-crystal phase, which he calls a cubic mesophase.¹ Adding salt removes the water, forcing proteins to crystallize.

Now Caffrey's lab has automated the method, which requires finely manipulating microscopic volumes of a lipid/protein mesophase that is as viscous as toothpaste. The robot his lab...