A new system for the deactivation of switch proteins has been recognized by researchers from Ruhr-Universität Bochum, headed by Professor Klaus Gerwert and Dr. Till Rudack from the Division of Biophysics, and the University of Uppsala in Sweden. Switch proteins like Ras regulate many processes in the body and have an effect on diseases akin to cancer. The study team published their report on the newly found mechanism in the present issue of the Journal of the American Chemical Society.
Bound to transfer proteins, the GTP molecule is significant for the deactivation of many of them. If one of many three phosphate groups is indifferent from GTP, the protein switches to “off,” thus affecting cellular processes. “The proteins are extremely environment-friendly and speed up reactions that would usually take billions of years so that they’re completed within a second,” says Klaus Gerwert.
At least one water molecule is always there in the deactivation course. So far, researchers assumed that this water molecule needed to be activated—namely by a reaction associate transferring a proton to the water molecule. “The character of the reaction companion has been argued for many years—is it the GTP itself or is it a protein element,” explains Carsten Kötting, one of the authors from the Bochum-based group. “In the current research, we’ve got surprisingly recognized an entirely new mechanism, where the activation occurs without any proton transfer by any means.”
Using computer-aided evaluation, the group examined all deactivation options for seven different switch protein methods. The researchers hence recognized different rates for the deactivation course. They compared the calculated activities with values gained in experiments via time-resolved infrared spectroscopy.