Weizmann Institute scientists explain how a plant substance blocks a key brain enzyme involved in Alzheimer's disease

REHOVOT, Israel -- December 27, 1999 -- Weizmann Institute researchers have revealed the exact nature of the 3-D interaction between galanthamine, a natural substance extracted from the common snowdrop (Galanthus nivalis) and the brain enzyme acetylcholinesterase (AChE). Their findings, appearing in the December 17 issue of the Federation of European Biochemical Societies (FEBS Letters), may provide crucial information in designing a new family of Alzheimers drugs.

Alzheimer's disease is a severe degenerative disorder causing memory loss and other cognitive deficits in roughly 10 percent of the elderly. One of its pathological hallmarks is the deterioration of nerve cells releasing acetylcholine a neurotransmitter that helps ferry messages in the form of nerve impulses between brain cells. The acetylcholine shortage that ensues is compounded by the action of acetylcholinesterase (AChE), the enzyme which breaks down acetylcholine in the body at an astonishing rate of 20,000 molecules per second.

Blocking acetylcholine breakdown

While scientists have yet to understand the cause of the disease, several Alzheimers drugs already exist, including Aricept, HupA (huperzine A), and Cognex (tacrine). Their underlying approach is to attempt to restore acetylcholine levels by inhibiting AChE activity.

Using X-ray crystallography, Dr. Harry Greenblatt of the Weizmann Institutes Department of Structural Biology, has revealed that galanthamine acts in a similar manner, replenishing acetylcholine levels by binding to AChEs active site and shutting off its "cutting machinery." Greenblatt conducted the research together with Dr. Gitay Kryger, and Professors Joel Sussman, and Israel Silman, all of the Weizmann Institute, as well as Dr. Terry Lewis of Zeneca Agrochemicals, in England.

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Contact: Jeffrey J Sussman
jeffrey@acwis.org
212-895-7951
American Committee for the Weizmann Institute of Science
26-Dec-1999