Columbia University's Bing Gong, MD, and colleagues describe the enzyme, called Uch-L1, in the journal Cell.
Alzheimer's disease erodes memory. Brains affected by Alzheimer's tend to be low in Uch-L1, according to Gong's team.
They used Uch-L1 to help mice with Alzheimer's brain plaque make new memories.
The enzyme "could be an attractive target for the development of new therapeutic approaches to Alzheimer's disease," write the researchers.
First, the scientists studied healthy mice without brain plaques. They gave some of the mice a shot that blocked Uch-L1.
Gong's team then put the mice in a special cage, one by one, and tried to train them, using a mild foot shock, to stay still. The mice that had gotten the enzyme-blocking shot were less likely to stay still in the cage.
Next, the researchers made a protein that includes Uch-L1. They injected that protein into mice that had brain plaque.
The mice that got the Uch-L1 shot were more likely to learn to stay still in the test cage, just like healthy mice, starting three weeks after the Uch-L1 injection.
The enzyme didn't destroy brain plaque's building blocks, which are called amyloid beta proteins. That might be a good thing, according to Columbia University's Ottavio Arancio, MD, PhD.
"Because the amyloid beta proteins that cause Alzheimer's may play a normal, important physiological role in the body, we can't destroy them as a therapy," says Arancio, who worked on the study, in a Columbia University news release.
"What makes this newly discovered enzyme exciting as a potentially effective therapy is that it restores memory without destroying amyloid beta proteins," Arancio adds.
The enzyme needs much more study before it's ready for human tests, the researchers note.
SOURCES: Gong, B. Cell, Aug. 25, 2006; vol 126: pp 775-788. News release, Columbia University Medical Center.
By Miranda Hitti
Reviewed by Brunilda Nazario