Secretases related to alzheimer's dementia

Abstract

This invention is directed to a novel β-secretase that produces the Aβ peptide found in Alzheimer's Disease. One β-secretase is a protein having a molecular weight of about 61, 81 or 88 kDa that cleaves an amyloid precursor protein (APP) substrate. Another is a protease complex having a molecular between about 180 and 200 kDa, which, in one embodiment, contains the 61, 81, and 88 kDa proteins and, in another embodiment, contains proteins having a molecular weight of about 66, 60, 33 and 29 kDa. Another β-secretase has a molecular weight between about 50 and 90 kDA. The invention is also directed to methods of selecting agents that inhibit Aβ peptide production and treating Alzheimer's disease in patients.

I claim:  
     
         1 . A substantially pure β-secretase comprising a protein having a molecular weight selected from the group consisting of about 61, 81 and 88 kiloDaltons (kDa) as determined by cleavage of an APP substrate in a non-reducing SDS-PAGE in gel activity assay.  
     
     
         2 . The β-secretase of  claim 1 , wherein the protein cleaves the APP substrate at a β-secretase recognition site.  
     
     
         3 . The β-secretase of  claim 2 , wherein the protein cleaves the β-secretase recognition site at a bond selected from the group consisting of Lys-Met and Val-Lys.  
     
     
         4 . The β-secretase of  claim 3 , wherein the protein cleaves the Lys-Met bond.  
     
     
         5 . A method of selecting an agent that inhibits a cleavage of an APP substrate comprising contacting the agent with the β-secretase of  claim 1  and selecting the agent that inhibits the cleavage of the APP substrate by the β-secretase.  
     
     
         6 . A method of inhibiting production of an Aβ peptide by a cell comprising contacting the cell with the agent selected by the method of  claim 5  and thereby inhibiting production of the Aβ peptide by the cell.  
     
     
         7 . A method of inhibiting production of an Aβ peptide by an Alzheimer's disease patient comprising administering to the patient the agent selected by the method of  claim 5  and thereby inhibiting production of the Aβ peptide by the Alzheimer's disease patient.  
     
     
         8 . A substantially pure protease complex having a molecular weight between about 180 and 200 kDa as determined by Sephacryl chromatography that cleaves an APP substrate.  
     
     
         9 . The protease complex of  claim 8 , wherein the protease complex cleaves the APP substrate at a β-secretase recognition site.  
     
     
         10 . The protease complex of  claim 9 , wherein the protease complex cleaves the β-secretase recognition site at a bond selected from the group consisting of Lys-Met and Val-Lys.  
     
     
         11 . The protease complex of  claim 10 , wherein the protease complex cleaves the Lys-Met bond.  
     
     
         12 . The protease complex of  claim 8 , further comprising proteins having a molecular weight selected from the group consisting of about 66, 60, 33 and 29 kDa as determined by a reducing SDS-PAGE in gel protein staining assay.  
     
     
         13 . The protease complex of  claim 8 , further comprising proteins having a molecular weight selected from the group consisting of about 61, 81 and 88 kDa as determined by cleavage of an APP substrate in a non-reducing SDS-PAGE in gel activity assay.  
     
     
         14 . A method of selecting an agent that inhibits a cleavage of an APP substrate comprising contacting the agent with the protease complex of  claim 8  and selecting the agent that inhibits the cleavage of the APP substrate by the protease complex.  
     
     
         15 . A method of inhibiting production of an Aβ peptide by a cell comprising contacting the cell with the agent selected by the method of  claim 14  and thereby inhibiting production of the Aβ peptide by the cell.  
     
     
         16 . A method of inhibiting production of an Aβ peptide by an Alzheimer's disease patient comprising administering to the patient the agent selected by the method of  claim 14  and thereby inhibiting production of the Aβ peptide by the Alzheimer's disease patient.  
     
     
         17 . A substantially pure β-secretase having a molecular weight between about 50 and 90 kDA as determined by Sephacryl chromatography and that cleaves an APP substrate.  
     
     
         18 . The β-secretase of  claim 17 , wherein the protease complex cleaves the APP substrate at a β-secretase recognition site.  
     
     
         19 . The β-secretase of  claim 18 , wherein the β-secretase cleaves the β-secretase recognition site at a bond selected from the group consisting of Met-Asp, Lys-Met and Val-Lys.  
     
     
         20 . The β-secretase of  claim 19 , wherein the β-secretase cleaves the Met-Asp bond.  
     
     
         21 . The β-secretase of  claim 17 , further comprising 2 proteins having different electronegative charges as determined by ion exchange chromatography.  
     
     
         22 . A method of selecting an agent that inhibits a cleavage of an APP substrate comprising contacting the agent with the β-secretase of  claim 17  and selecting the agent that inhibits the cleavage of the APP substrate by the β-secretase.  
     
     
         23 . A method of inhibiting production of an Aβ peptide by a cell comprising contacting the cell with the agent selected by the method of  claim 22  and thereby inhibiting production of the Aβ peptide by the cell.  
     
     
         24 . A method of inhibiting production of an Aβ peptide by an Alzheimer's disease patient comprising administering to the patient the agent selected by the method of  claim 22  and thereby inhibiting production of the Aβ peptide by the Alzheimer's disease patient.