Smrcka's team performed a computer-simulated experiment to see which drug-like molecules from an existing database of 1990 known structures would bind tightly to the hotspot, and to rank them. In general, tight binding suggests that a drug candidate has the potential to remain bound to its target long enough to have the desired effect. Of the compounds found through the screen, one, called M119, had a high enough affinity for the hotspot to be chosen as a lead compound in further experiments. In a standard drug discovery technique, researchers collected several compounds (21 in this case) similar to their lead compound to see if any small change to the lead would drastically affect its drug potential.
Researchers tested two compounds as a proof of general principle, M119 and M201, which bound most effectively to the hotspot. For the purposes of the experiment, researchers chose to test the affect of M119 and M201 on two biological systems that the G protein gamma-beta subunit controls. In one, white blood cells home in on the site of infection. The other involves pain relief brought about by morphine.
In white blood cells, the free G protein gamma-beta subunit activates enzymes that allow the cells to home in on the site of infection. Researchers found that pre-treatment of white blood cells with M119 reduced activation of enzymes that encourage inflammation. That should in theory keep the white blood cells from mistakenly causing inflammation as they do in patients with rheumatoid arthritis or heart disease. While M119 did block the action of an enzyme involved in inflammation (PI3kinase), it did not block related signals necessary for basic cell function.
In addition, M119 was shown to block activation of phospholipase C, which plays a role in morphine's ability to provide pain relief. In early studies, administration of M119 with morphine resulted
Contact: Greg Williams
University of Rochester Medical Center