The research was carried out within the framework of a project (RAPID) at the Uppsala University Center for Structural Biology, Medical Chemistry, and Computer Chemistry, which was established last year and is directed by Professor Alwyn Jones. The aim is to develop drugs for some of the most severe and widely spread diseases in the world, such as malaria and TB. The results, which recently came out as an “accelerated publication” in the journal Biochemistry, are the work of Professor Johan Åqvist and doctoral student Sinisa Bjelic.
“The enzyme we studied is a new type, with previously unknown catalyst groups. This made it especially interesting as a target molecule for new drugs. Using only computer calculations, we succeeded in revealing both what it looks like and how it functions. It’s the first time anybody ever did that,” says Johan Åqvist.
They started by comparing the enzyme’s amino acid sequence with other known sequences. Then they ran computer simulations of how it might move in order to find possible structures, after which they looked at plausible combinations for how a substrate, a small peptide, might stick to the enzyme. In this way it was possible to predict the structure of the enzyme, how the substrate bonds, and the mechanism and rapidity of the chemical reaction. The fit with experimental data was good.
“In the past researchers have managed to predict reaction mechanisms on the basis of known structures, but this time we started from scratch.”
The malaria parasite under study, Plasmodium falciparum, has several enzymes that directly attack hemoglobin in the blood when it invades. There is a tremendous interest in these enzymes among drug researchers. Today 1-3 million people die of malaria every year, and there is growing concern that the numbers will increase further.
“Millions of people are infected, and the parasite quickly develops resistance to new drugs,” says Johan Åqvist.
Research in the RAPID project is funded by the Swedish Foundation for Strategic Research.