Modified Fluorescent Proteins for Detecting Protease Activity
Patent Information:
Filing Country: USA
Application No: 09/551380
Filing Date: 18 April 2000
Patent No: 7049400
Issue Date: 23 May 2006
Inventor 1: Prof. Donald Choy, CHANG
Inventor 2: Dr. Qian, LUO

Programmed cell death is a very important cellular process that is critically involved in many diseases. A key step in the programmed cell death is the activation of a series of intracellular proteases, such as caspase-3. The invention is a novel method of detecting the early stage of programmed cell death in living cells. Green Fluorescent Protein (GFP) in the jellyfish Aequorea victoria is discovered to be used as a protein detector. When the cloned gene of GFP is expressed in host cells, it can produce an endogenous fluorescent protein without requiring adding converting enzymes or substrates. A molecular probe has been designed to assay the caspase activity by inserting the gene encoding the recognition sequence into the GFP gene. When this engineered gene is expressed in a cell, its gene product (a protein) will become a substrate of the specific caspase and can be cleaved by the caspase upon its activation and greatly change the fluorescent properties of the molecule. Such a change of fluorescence can be easily detected by optical means and thus can be used to assay whether the cells are undergoing programmed cell death or not. Programmed cell death plays a critical role in many important diseases, including many types of cancer, AIDS, and auto-immune diseases. Drugs that can facilitate detection of programmed cell death in malfunctioning cells will be potentially useful in controlling these diseases. This invention thus will be highly useful to the pharmaceutical industry for rapid screening of drugs.
Potential Application   Advantage
- Drugs development for cancer, AIDS, and auto-immune diseases
- Can be used for drugs screening and toxicity tests
  1. The detection procedure is extremely simple
2. Useful for large scale screening of drugs that can either promote or block programmed cell death
3. Easily adapted to detect activation of other proteases by changing the sensor sequence
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