Aug. 24, 2000 Washington D.C., August 23 -- A "striking similarity" between proteins involved in the early stages of Alzheimer's disease and mad cow disease was described here today at the 220th national meeting of the American Chemical Society, the world's largest scientific society. The theory, if verified by other researchers, could help focus efforts to develop preventive drugs, according to the study's lead researcher, Chi Ming Yang, Ph.D., a professor of chemistry at Nankai University in Tianjin, China.
Prion diseases — which include, among others, neurodegenerative diseases such as mad cow disease and its human counterpart, Creutzfeldt-Jakob disease — are caused by a malfunctioning prion protein. In Alzheimer's disease, another neurodegenerative disease, the amyloid precursor protein has been implicated.
Using computer modeling, Yang discovered a similar pattern of amino acids in the prion protein and the amyloid precursor protein: a reductive amino acid followed by three non-reductive amino acids.
"This suggests a common molecular mechanism underlying the initiation stages of sporadic Alzheimer's disease and both sporadic and genetic prion diseases," says Yang.
Reductive amino acids are more prone to damage by oxygen-containing free radicals (molecules with a highly reactive unpaired electron) than other amino acids, explained Yang. Normally, the body can clear itself of free radicals. But with age, this system may fail. When enough free radicals accumulate to damage a protein molecule, it can malfunction, he says.
Proteins typically fold into specific three-dimensional structures that determine their functions. A malfunctioning protein may remain partially unfolded, which can place different amino acids in close proximity, Yang explained. In the case of Alzheimer's and prion diseases, the reductive amino acids in close proximity can lead to the formation of protein plaques, according to Yang.
Although Alzheimer's and prion diseases seem to start in similar ways, they progress differently. This may explain why Alzheimer's disease advances at a much slower pace than Creutzfeldt-Jakob disease, says Yang.
The paper on this research, PHYS 460, will be presented at 7 p.m., Wednesday, Aug. 23, in the Washington Convention Center, Exhibit Hall D.
Chi Ming Yang, Ph.D., is a chemistry professor at Nankai University, Tianjin, China.
A nonprofit organization with a membership of 161,000 chemists and chemical engineers, the American Chemical Society publishes scientific journals and databases, convenes major research conferences, and provides educational, science policy and career programs in chemistry. Its main offices are in Washington, D.C., and Columbus, Ohio.
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