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Cathepsin D From Alzheimer's-diseased and Normal Brains

Cathepsin D From Alzheimer's-diseased and Normal Brains

R E Kohnken, U S Ladror, G T Wang, T F Holzman, B E Miller, G A Krafft

Exp Neurol. 1995 Jun;133(2):105-12.

PMID: 7649217

Abstract:

An acid protease activity from human brain was found to cleave a fluorogenic peptide substrate encompassing the amino terminus of Alzheimer's amyloid-beta peptide (A beta). The protease was isolated and determined to be cathepsin D based on chromatographic, immunological, and enzymatic data. Analysis of the cleavage sites indicated that cathepsin D hydrolyzed the methionine--aspartate bond generating the in vivo amino terminus of A beta. These data suggested that cathepsin D could be involved in amyloidogenic processing of the amyloid precursor protein. Consequently, cathepsin D from both Alzheimer's-diseased and control brains was compared to determine whether there were any differences which could account for an increase in A beta production in Alzheimer's disease. No differences were detected in isoform composition or tissue content of cathepsin D as measured by 2-D IEF-SDS-PAGE. Enzymological characterization of brain cathepsin D demonstrated that it could undergo a previously undescribed pH-dependent reversible activation. However, that activation appeared identical for both AD and normal brain enzymes. These data demonstrate that concentration, isoform distribution, and several enzymological characteristics of cathepsin D are not distinguishable between AD and normal brain. The pH dependence of cathepsin D activity suggests, however, that its intracellular localization may be important in considering the potential role of cathepsin D in Alzheimer's disease.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
IAR42415991	Cathepsin S Substrate, Fluorogenic			Price

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