The authors designed the molecular probe to be recognized by a single protease rather than by the many proteases that are present in human tissues. That is half of the probe. The other half of the probe involves an optical technique used to measure activity. This approach relies upon the use of two engineered fluorescent proteins, derived from marine organisms, that absorb and emit light in a process called FRET, or Forster resonance energy transfer.
To prepare the probes, the researchers introduced a gene that encodes the probe into the bacteria E. coli. Then they produced and purified significant quantities of the probe. All of the information needed for the probe is encoded by a DNA sequence. The probes are easy and inexpensive to produce, as well as easily shared with other researchers.
In addition to studying cancer, similarly constructed probes have ramifications for studying Alzheimer's disease, arthritis and connective tissue diseases, bacterial infections, viruses, and many other diseases.
"The fact that you can generalize the concept, and the way you make these probes, to many systems, makes it attractive," said Daugherty. "We happen to study the activity of this protease and a certain type of tumor cells that are derived from cancer patients. But you could apply this to hundreds of molecules and really develop a working understanding of how groups of proteases function together in cell biology."
In individuals with rheumatoid arthritis, for example, there is increased production of proteases, including the one studied by Daugherty's team. This protease mediates collagen breakdown and joint destruction. "If you've got an enzyme that can chew up collagen and you've got lots of collagen in your joints, then you would expect that you would see more rapi
|Contact: Gail Gallessich|
University of California - Santa Barbara