Dreyer R N, Bausch K M, Fracasso P, Hammond L J, Wunderlich D, Wirak D O, Davis G, Brini C M, Buckholz T M, König G
Institute for Molecular Biologicals, Miles Inc., Pharmaceuticals Division, West Haven, Connecticut 06516.
Eur J Biochem. 1994 Sep 1;224(2):265-71. doi: 10.1111/j.1432-1033.1994.00265.x.
A major pre-beta-amyloid protein695 (APP695) processing activity from Alzheimer's disease brain extracts was identified and found to be indistinguishable from the activity of cathepsin D.APP695 processing activity cleaved APP695 into a series of fragments that reacted on immunoblots to a monoclonal antibody (C286.8a) against beta-amyloid-(1-7)-peptide and cleaved N-dansyl-APP-(591-601)-amide at the Glu-Val and Met-Asp bonds. Fragments of 5.5 kDa and 10-12 kDa were formed from the cleavage of APP695 by cathepsin D at the Glu593-Val594 bond, and had the same N-terminus as a minor form of beta-amyloid released by cells. The Lys595-->Asn and Met596-->Leu substitutions found in a pedigree of familial Alzheimer's disease, increased the cathepsin D-catalyzed rate of accumulation of 5.5 kDa and 10-12 kDa C286.8a-reactive fragments 5-10fold. This substitution also increased the rate of N-dansyl-APP-(591-601)-amide cleavage at the Xaa-Asp bond by up to 41-fold. These observations suggest a role of cathepsin D in beta-amyloid formation under certain circumstances.
在阿尔茨海默病脑提取物中鉴定出一种主要的前β-淀粉样蛋白695（APP695）加工活性，发现其与组织蛋白酶D的活性无法区分。APP695加工活性将APP695切割成一系列片段，这些片段在免疫印迹上与针对β-淀粉样蛋白（1-7）肽的单克隆抗体（C286.8a）发生反应，并在Glu-Val和Met-Asp键处切割N-丹磺酰基-APP-（591-601）-酰胺。组织蛋白酶D在Glu593-Val594键处切割APP695形成5.5 kDa和10 - 12 kDa的片段，这些片段的N端与细胞释放的一种次要形式的β-淀粉样蛋白相同。在一个家族性阿尔茨海默病家系中发现的Lys595→Asn和Met596→Leu替代，使组织蛋白酶D催化的5.5 kDa和10 - 12 kDa C286.8a反应性片段的积累速率提高了5至10倍。这种替代还使Xaa-Asp键处N-丹磺酰基-APP-（591-601）-酰胺的切割速率提高了41倍。这些观察结果表明组织蛋白酶D在某些情况下在β-淀粉样蛋白形成中起作用。
