Possible Alzheimer's Enzyme Found
Paul Recer,
Associated Press Writer

6:03 PM EST; October 22, 1999; Washington, D.C. (AP) -- An enzyme that is thought to be part of the Alzheimer's disease process may have been isolated by California researchers, a discovery that could lead to new drugs for the brain-destroying disease. Researchers report Friday in the journal Science that they have found an enzyme called beta-secretase that has been linked to the formation of beta-amyloid, a protein that kills neurons in the brains of Alzheimer's patients.

The enzyme works by cutting beta-amyloid from another compound called Amyloid Precursor Protein (APP). Researchers believe that identifying the correct enzyme could lead to drugs that would block beta-amyloid formation. But even if drugs are found to inhibit the buildup of beta-amyloid, experts said they are still uncertain if this alone will slow or halt Alzheimer's disease. "The case is not airtight," Science said in a commentary. Alzheimer's disease is a lethal disorder that gradually destroys the brain. Its most prominent feature is the slow loss of memory and the ability to reason. Eventually even the brain functions vital to life are destroyed.

Ever since the beta-secretase enzyme was identified as part of the disease process, many laboratories have attempted to isolate it. At least a dozen research teams have claimed to have made the discovery, but the findings have been disputed by others. Another California firm, Elan Pharmaceuticals of South San Francisco, holds a patent on what the company claims is beta-secretase. But theirs is different from the protein identified by Amgen. Still another enzyme has been isolated by SmithKline Beecham, and researchers from that drug firm plan to describe their finding at a meeting in Miami this week of the Society for Neuroscience.

However, Science magazine reports that a number of independent experts say they find the claim by Amgen researchers to be credible. "They have both cell biological evidence and evidence that the purified enzyme acts with the (right) specificity," Bart De Strooper, a Belgian neuroscientist, said in Science. Sangram Sisodia, a University of Chicago beta-amyloid specialist who also commented in the journal, called the Amgen claim "incontrovertible."