It has been known since the early 1970s that cytochrome P450 (CYP) enzymes are involved in drug metabolism, and it has been shown in numerous cases that activities of the CYP family account for serious side effects in all sorts of medications. But until now no one had been able to describe the 3-dimensional structure of these crucial enzymes.

The main obstacles, said Harren Jhoti, co-founder and CSO of Astex Technology Ltd. (Cambridge, U.K.), "have been aggregation and stability problems, as these enzymes are membrane proteins."