X-ray laser helps fight sleeping sickness

An international group of scientists working at the National Accelerator Laboratory of the Department of Energy's (DOE) Stanford Linear Accelerator Centre (SLAC) has mapped a weak spot in the parasite that causes African sleeping sickness, pinpointing a promising new target for treating a disease that kills tens of thousands of people each year.

The results are already being enlisted in the effort to combat the disease, which is transmitted by tsetse flies infected with the single-celled parasite. The study also marks a milestone in using X-ray lasers, such as SLAC's Linac Coherent Light Source (LCLS), to determine the structures of biological molecules that are important for human health.

"This is the first new biological structure solved with a free-electron laser," said Henry Chapman of the Center for Free-Electron Laser Science in Hamburg, Germany, one of the leaders of the research team.

Lars Redecke, another team leader, said, ''This is really a landmark in structural biology, and a significant step toward developing a new drug." Redecke is a structural biologist at the Joint Laboratory for Structural Biology of Infection and Inflammation of Hamburg and Lübeck universities in Germany.

About 60 million people across Africa are at risk of contracting African sleeping sickness, which kills an estimated 30,000 people each year. Existing drug treatments can be painful and cause serious side effects, and the parasites are becoming increasingly drug-resistant.

One of the parasite's main weapons is an enzyme that breaks down proteins in its victims. Scientists hope to stop the disease by mimicking a natural ''inhibitor'' that keeps the enzyme in check until the parasite invades its victim's bloodstream. But the parasite's enzyme is so similar to one in humans that blocking it could also harm the patient, and researchers needed more detailed information about its structure to design a drug that attacks only the parasite.