Now come the protegrins, a new class of antibacterial agents that were discovered in the white blood cells of pigs in 1993 by UCLA's Lehrer. Found in all living creatures, protegrins form the first line against invading bacteria. IntraBiotics Pharmaceuticals Inc. of Mountain View, Calif., has licensed the patented protegrin technology from UCLA and has developed two antibiotic products now in clinical trials. Neither Chicago researcher has any current finanical interest in protegrin, but the UCLA co-authors do. Protegrins show promise as an alternative to antibiotics because they function differently.
Antibiotics kill bacteria by reacting with a specific protein at the surface of cell membranes.
Protegrins apparently kill bacteria by more directly penetrating and fatally disrupting cellular membranes, though exactly how remains unclear. The initial problem with protegrins was their tendency to damage human red blood cells. In separate work, Waring and Lehrer seem to have succeeded in altering that tendency by substituting certain amino acids in the sequence, Gidalevitz said. The research team injected protegrins into a preparation of each model system that was only one layer of molecules thick. Then they used fluorescence microscopy and X-ray reflectivity to image and measure the molecular interaction.