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Robert Vassar - One of the best experts on this subject based on the ideXlab platform.
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Beta-Secretase, APP and ABeta in Alzheimer's disease.
Sub-cellular biochemistry, 2020Co-Authors: Robert VassarAbstract:Amyloid plaques, hallmark neuropathological lesions in Alzheimer's disease (AD) brain, are composed of the Beta-amyloid peptide (ABeta). A large body of evidence suggests ABeta is central to the pathophysiology of AD and is likely to start this intractable neurodegenerative disorder. Mutations in three genes (amyloid precursor protein/APP, presenilin1, presenilin2) cause early on-set familial AD by increasing synthesis of the toxic 42 amino acid species of ABeta (ABeta42). Fibrillar ABeta in amyloid plaques appears to cause neurodegeneration, although recent studies suggest soluble ABeta oligomers may also be neurotoxic. Regardless, given the strong correlation between ABeta and AD, therapeutic strategies to lower cerebral ABeta levels should prove beneficial for the treatment of AD. ABeta is derived from APP via cleavage by two proteases, Beta- and gamma-Secretase. Beta-Secretase, recently identified as the novel aspartic protease BACEI, initiates the formation of ABeta. Consequently, BACE1 in principle is an excellent therapeutic target for strategies to reduce the production of ABeta in AD. However, the discovery of the homologue BACE2 raised the question of whether it too may be a Beta-Secretase. To settle this issue, our group and others have used gene targeting to generate BACE1 deficient (knockout) mice. These BACEI knockout mice have been instrumental in validating BACEI as the authentic Beta-Secretase in vivo. Here, I review the roles of BACE1, APP, and ABeta in AD and discuss the implications of therapeutic approaches that target BACE1 for the treatment of AD.
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BACE1, the Alzheimer’s Beta-Secretase enzyme, in health and disease.
Molecular Neurodegeneration, 2012Co-Authors: Robert VassarAbstract:The Beta-amyloid (ABeta) peptide is the major constituent of amyloid plaques in Alzheimer’s disease (AD) brain and is likely to play a central role in the pathogenesis of this devastating neurodegenerative disorder. The Beta-Secretase, Beta-site amyloid precursor protein cleaving enzyme 1 (BACE1; also called Asp2, memapsin 2), is the enzyme responsible for initiating the generation of ABeta. Thus, BACE1 is a prime drug target for the therapeutic inhibition of ABeta production for the treatment or prevention of AD. Since its discovery over 10 years ago, much has been learned about BACE1. This seminar will describe BACE1 properties, physiological functions, and dysregulation in AD. The therapeutic potential of BACE1 inhibitors for AD will also be considered. Particular focus will be placed upon our novel results demonstrating a role of BACE1 in the axon guidance of olfactory sensory neuron axons to specific odorant receptor glomeruli in the olfactory bulb and the therapeutic implications of these findings.
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bace1 the alzheimer s Beta Secretase enzyme in health and disease
Molecular Neurodegeneration, 2012Co-Authors: Robert VassarAbstract:The Beta-amyloid (ABeta) peptide is the major constituent of amyloid plaques in Alzheimer’s disease (AD) brain and is likely to play a central role in the pathogenesis of this devastating neurodegenerative disorder. The Beta-Secretase, Beta-site amyloid precursor protein cleaving enzyme 1 (BACE1; also called Asp2, memapsin 2), is the enzyme responsible for initiating the generation of ABeta. Thus, BACE1 is a prime drug target for the therapeutic inhibition of ABeta production for the treatment or prevention of AD. Since its discovery over 10 years ago, much has been learned about BACE1. This seminar will describe BACE1 properties, physiological functions, and dysregulation in AD. The therapeutic potential of BACE1 inhibitors for AD will also be considered. Particular focus will be placed upon our novel results demonstrating a role of BACE1 in the axon guidance of olfactory sensory neuron axons to specific odorant receptor glomeruli in the olfactory bulb and the therapeutic implications of these findings.
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bace1 the Beta Secretase enzyme in alzheimer s disease
Journal of Molecular Neuroscience, 2004Co-Authors: Robert VassarAbstract:: Data that have accumulated for well over a decade have implicated the Beta-amyloid (ABeta) peptide as a central player in the pathogenesis of Alzheimer's disease (AD). Amyloid plaques, composed primarily of ABeta progressively form in the brains of AD patients, and mutations in three genes (amyloid precursor protein [APP] and presenilin 1 and 2 [PS1 and PS2]) cause early-onset familial AD (FAD) by directly increasing production of the toxic, plaque-promoting ABeta42 peptide. Given the strong association between ABeta and AD, it is likely that therapeutic strategies to lower the levels of ABeta in the brain should prove beneficial for the treatment of AD. One such strategy could involve inhibiting the enzymes that generate ABeta. ABeta is a product of catabolism of the large type-I membrane protein APP. Two proteases, called Beta- and gamma-Secretase, endoproteolyze APP to liberate the ABeta peptide. Recently, the molecules responsible for these proteolytic activities have been identified. Several lines of evidence suggest that the PS1 and PS2 proteins are gamma-Secretase, and the identity of Beta-Secretase has been shown to be the novel transmembrane aspartic protease, Beta-site APP-cleaving enzyme 1 (BACE1; also called Asp2 and memapsin 2). BACE2, a protease homologous to BACE1, was also identified, and together the two enzymes define a new family of transmembrane aspartic proteases. BACE1 exhibits all the functional properties of Beta-Secretase, and as the key enzyme that initiates the formation of ABeta, BACE1 is an attractive drug target for AD. This review discusses the identification and initial characterization of BACE1 and BACE2, and summarizes recent studies of BACE1 knockout mice that have validated BACE1 as the authentic Beta-Secretase in vivo.
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Beta-Secretase cleavage of Alzheimer's amyloid precursor protein by the transmembrane aspartic protease BACE.
Science, 1999Co-Authors: Robert Vassar, Brian D. Bennett, Safura Babu-khan, Steve Kahn, Elizabeth A. Mendiaz, Paul Denis, David B. Teplow, Sandra Ross, Patricia Amarante, Richard LoeloffAbstract:Cerebral deposition of amyloid Beta peptide (ABeta) is an early and critical feature of Alzheimer's disease. ABeta generation depends on proteolytic cleavage of the amyloid precursor protein (APP) by two unknown proteases: Beta-Secretase and gamma-Secretase. These proteases are prime therapeutic targets. A transmembrane aspartic protease with all the known characteristics of Beta-Secretase was cloned and characterized. Overexpression of this protease, termed BACE (for Beta-site APP-cleaving enzyme) increased the amount of Beta-Secretase cleavage products, and these were cleaved exactly and only at known Beta-Secretase positions. Antisense inhibition of endogenous BACE messenger RNA decreased the amount of Beta-Secretase cleavage products, and purified BACE protein cleaved APP-derived substrates with the same sequence specificity as Beta-Secretase. Finally, the expression pattern and subcellular localization of BACE were consistent with that expected for Beta-Secretase. Future development of BACE inhibitors may prove beneficial for the treatment of Alzheimer's disease.
Ping He - One of the best experts on this subject based on the ideXlab platform.
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PET imaging of Beta-Secretase 1 in the human brain: radiation dosimetry, quantification, and test-retest examination of [^18F]PF-06684511
European Journal of Nuclear Medicine and Molecular Imaging, 2020Co-Authors: Ryosuke Arakawa, Akihiro Takano, Per Stenkrona, Vladimir Stepanov, Mahabuba Jahan, Per Grybäck, Martin Bolin, Laigao Chen, Lei Zhang, Ping HeAbstract:Purpose Beta-Secretase 1 (BACE1) enzyme is implicated in the pathophysiology of Alzheimer’s disease. [^18F]PF-06684511 is a positron emission tomography (PET) radioligand for imaging BACE1. Despite favorable brain kinetic properties, the effective dose (ED) of [^18F]PF-06684511 estimated in non-human primates was relatively high. This study was therefore designed to evaluate the whole-body distribution, dosimetry, quantification, and test-retest reliability of imaging brain BACE1 with [^18F]PF-06684511 in healthy volunteers. Methods Five subjects were studied for the dosimetry study. Whole-body PET was performed for 366 min with 4 PET-CT sessions. Estimates of the absorbed radiation dose were calculated using the male adult model. Eight subjects participated in the test-retest study. Brain PET measurements were conducted for 123 min with an interval of 5 to 19 days between test and retest conditions. The total distribution volume ( V _T) was estimated with one-tissue (1T), two-tissue (2T), compartment model (CM), and graphical analysis. Test-retest variability (TRV) and intraclass correlation coefficient (ICC) of V _T were calculated as reliability measures. Results In the dosimetry study, the highest uptake was found in the liver (25.2 ± 2.3 %ID at 0.5 h) and the largest dose was observed in the pancreas (92.9 ± 52.2 μSv/MBq). The calculated ED was 24.7 ± 0.8 μSv/MBq. In the test-retest study, 2TCM described the time-activity curves well. V _T (2TCM) was the highest in the anterior cingulate cortex (6.28 ± 1.09 and 6.85 ± 0.81) and the lowest in the cerebellum (4.23 ± 0.88 and 4.20 ± 0.75). Mean TRV and ICC of V _T (2TCM) were 16.5% (12.4–20.5%) and 0.496 (0.291–0.644). Conclusion The ED of [^18F]PF-06684511 was similar to other ^18F radioligands, allowing repeated PET measurements. 2TCM was the most appropriate quantification method. TRV of V _T was similar to other radioligands without a reference region, albeit with lower ICC. These data indicated that [^18F]PF-06684511 is a suitable radioligand to measure BACE1 level in the human brain. Trial registration EudraCT 2016-001110-19 (registered 2016-08-08)
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pet imaging of Beta Secretase 1 in the human brain radiation dosimetry quantification and test retest examination of 18f pf 06684511
European Journal of Nuclear Medicine and Molecular Imaging, 2020Co-Authors: Ryosuke Arakawa, Akihiro Takano, Per Stenkrona, Vladimir Stepanov, Mahabuba Jahan, Per Grybäck, Martin Bolin, Laigao Chen, Lei Zhang, Ping HeAbstract:PURPOSE: Beta-Secretase 1 (BACE1) enzyme is implicated in the pathophysiology of Alzheimer's disease. [18F]PF-06684511 is a positron emission tomography (PET) radioligand for imaging BACE1. Despite favorable brain kinetic properties, the effective dose (ED) of [18F]PF-06684511 estimated in non-human primates was relatively high. This study was therefore designed to evaluate the whole-body distribution, dosimetry, quantification, and test-retest reliability of imaging brain BACE1 with [18F]PF-06684511 in healthy volunteers. METHODS: Five subjects were studied for the dosimetry study. Whole-body PET was performed for 366 min with 4 PET-CT sessions. Estimates of the absorbed radiation dose were calculated using the male adult model. Eight subjects participated in the test-retest study. Brain PET measurements were conducted for 123 min with an interval of 5 to 19 days between test and retest conditions. The total distribution volume (VT) was estimated with one-tissue (1T), two-tissue (2T), compartment model (CM), and graphical analysis. Test-retest variability (TRV) and intraclass correlation coefficient (ICC) of VT were calculated as reliability measures. RESULTS: In the dosimetry study, the highest uptake was found in the liver (25.2 ± 2.3 %ID at 0.5 h) and the largest dose was observed in the pancreas (92.9 ± 52.2 μSv/MBq). The calculated ED was 24.7 ± 0.8 μSv/MBq. In the test-retest study, 2TCM described the time-activity curves well. VT (2TCM) was the highest in the anterior cingulate cortex (6.28 ± 1.09 and 6.85 ± 0.81) and the lowest in the cerebellum (4.23 ± 0.88 and 4.20 ± 0.75). Mean TRV and ICC of VT (2TCM) were 16.5% (12.4-20.5%) and 0.496 (0.291-0.644). CONCLUSION: The ED of [18F]PF-06684511 was similar to other 18F radioligands, allowing repeated PET measurements. 2TCM was the most appropriate quantification method. TRV of VT was similar to other radioligands without a reference region, albeit with lower ICC. These data indicated that [18F]PF-06684511 is a suitable radioligand to measure BACE1 level in the human brain. TRIAL REGISTRATION: EudraCT 2016-001110-19 (registered 2016-08-08).
Ryosuke Arakawa - One of the best experts on this subject based on the ideXlab platform.
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PET imaging of Beta-Secretase 1 in the human brain: radiation dosimetry, quantification, and test-retest examination of [^18F]PF-06684511
European Journal of Nuclear Medicine and Molecular Imaging, 2020Co-Authors: Ryosuke Arakawa, Akihiro Takano, Per Stenkrona, Vladimir Stepanov, Mahabuba Jahan, Per Grybäck, Martin Bolin, Laigao Chen, Lei Zhang, Ping HeAbstract:Purpose Beta-Secretase 1 (BACE1) enzyme is implicated in the pathophysiology of Alzheimer’s disease. [^18F]PF-06684511 is a positron emission tomography (PET) radioligand for imaging BACE1. Despite favorable brain kinetic properties, the effective dose (ED) of [^18F]PF-06684511 estimated in non-human primates was relatively high. This study was therefore designed to evaluate the whole-body distribution, dosimetry, quantification, and test-retest reliability of imaging brain BACE1 with [^18F]PF-06684511 in healthy volunteers. Methods Five subjects were studied for the dosimetry study. Whole-body PET was performed for 366 min with 4 PET-CT sessions. Estimates of the absorbed radiation dose were calculated using the male adult model. Eight subjects participated in the test-retest study. Brain PET measurements were conducted for 123 min with an interval of 5 to 19 days between test and retest conditions. The total distribution volume ( V _T) was estimated with one-tissue (1T), two-tissue (2T), compartment model (CM), and graphical analysis. Test-retest variability (TRV) and intraclass correlation coefficient (ICC) of V _T were calculated as reliability measures. Results In the dosimetry study, the highest uptake was found in the liver (25.2 ± 2.3 %ID at 0.5 h) and the largest dose was observed in the pancreas (92.9 ± 52.2 μSv/MBq). The calculated ED was 24.7 ± 0.8 μSv/MBq. In the test-retest study, 2TCM described the time-activity curves well. V _T (2TCM) was the highest in the anterior cingulate cortex (6.28 ± 1.09 and 6.85 ± 0.81) and the lowest in the cerebellum (4.23 ± 0.88 and 4.20 ± 0.75). Mean TRV and ICC of V _T (2TCM) were 16.5% (12.4–20.5%) and 0.496 (0.291–0.644). Conclusion The ED of [^18F]PF-06684511 was similar to other ^18F radioligands, allowing repeated PET measurements. 2TCM was the most appropriate quantification method. TRV of V _T was similar to other radioligands without a reference region, albeit with lower ICC. These data indicated that [^18F]PF-06684511 is a suitable radioligand to measure BACE1 level in the human brain. Trial registration EudraCT 2016-001110-19 (registered 2016-08-08)
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pet imaging of Beta Secretase 1 in the human brain radiation dosimetry quantification and test retest examination of 18f pf 06684511
European Journal of Nuclear Medicine and Molecular Imaging, 2020Co-Authors: Ryosuke Arakawa, Akihiro Takano, Per Stenkrona, Vladimir Stepanov, Mahabuba Jahan, Per Grybäck, Martin Bolin, Laigao Chen, Lei Zhang, Ping HeAbstract:PURPOSE: Beta-Secretase 1 (BACE1) enzyme is implicated in the pathophysiology of Alzheimer's disease. [18F]PF-06684511 is a positron emission tomography (PET) radioligand for imaging BACE1. Despite favorable brain kinetic properties, the effective dose (ED) of [18F]PF-06684511 estimated in non-human primates was relatively high. This study was therefore designed to evaluate the whole-body distribution, dosimetry, quantification, and test-retest reliability of imaging brain BACE1 with [18F]PF-06684511 in healthy volunteers. METHODS: Five subjects were studied for the dosimetry study. Whole-body PET was performed for 366 min with 4 PET-CT sessions. Estimates of the absorbed radiation dose were calculated using the male adult model. Eight subjects participated in the test-retest study. Brain PET measurements were conducted for 123 min with an interval of 5 to 19 days between test and retest conditions. The total distribution volume (VT) was estimated with one-tissue (1T), two-tissue (2T), compartment model (CM), and graphical analysis. Test-retest variability (TRV) and intraclass correlation coefficient (ICC) of VT were calculated as reliability measures. RESULTS: In the dosimetry study, the highest uptake was found in the liver (25.2 ± 2.3 %ID at 0.5 h) and the largest dose was observed in the pancreas (92.9 ± 52.2 μSv/MBq). The calculated ED was 24.7 ± 0.8 μSv/MBq. In the test-retest study, 2TCM described the time-activity curves well. VT (2TCM) was the highest in the anterior cingulate cortex (6.28 ± 1.09 and 6.85 ± 0.81) and the lowest in the cerebellum (4.23 ± 0.88 and 4.20 ± 0.75). Mean TRV and ICC of VT (2TCM) were 16.5% (12.4-20.5%) and 0.496 (0.291-0.644). CONCLUSION: The ED of [18F]PF-06684511 was similar to other 18F radioligands, allowing repeated PET measurements. 2TCM was the most appropriate quantification method. TRV of VT was similar to other radioligands without a reference region, albeit with lower ICC. These data indicated that [18F]PF-06684511 is a suitable radioligand to measure BACE1 level in the human brain. TRIAL REGISTRATION: EudraCT 2016-001110-19 (registered 2016-08-08).
Pia Davidsson - One of the best experts on this subject based on the ideXlab platform.
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measurement of alpha and Beta Secretase cleaved amyloid precursor protein in cerebrospinal fluid from alzheimer patients
Experimental Neurology, 2003Co-Authors: Annika Olsson, Kina Hoglund, Magnus Sjogren, Niels Andreasen, Lennart Minthon, Lars Lannfelt, Katharina Buerger, Hansjurgen Moller, Harald Hampel, Pia DavidssonAbstract:One of the major histopathological hallmarks of Alzheimer's disease (AD) is redundant senile plaques mainly composed of Beta-amyloid (ABeta) aggregates. Alternative cleavage of the amyloid precursor protein (APP), occurring in both normal and AD subjects, results in the generation and secretion of soluble APP (sAPP) and ABeta. We examined the cerebrospinal fluid (CSF) for alpha- and Beta-Secretase cleaved sAPP (alpha-sAPP and Beta-sAPP) in 81 sporadic AD patients, 19 patients with mild cognitive impairment, and 42 healthy controls by using newly developed sandwich enzyme-linked immunosorbent assay methods. We found that neither the level of CSF-alpha-sAPP nor CSF-Beta-sAPP differed between sporadic AD patients and healthy controls. These findings further support the conclusion that there is no change in APP expression in sporadic AD. However, the level of CSF-Beta-sAPP was significantly increased in patients with mild cognitive impairment compared to controls. We also investigated the relationship between the CSF level of alphaBeta-sAPP and ABeta(42) and the apoE epsilon4 (apoFA.) allele. Significantly lower levels of CSF-alpha-sAPP were found in AD patients possessing one or two apoE4 alleles than in those not possessing the apoE4 allele. Neither the levels of CSF-Beta-sAPP nor CSF-ABeta(42) differed when comparing ApoE4 allele-positive with allele-negative individuals. (C) 2003 Elsevier Science (USA). All rights reserved. (Less)
Vincenza Andrisano - One of the best experts on this subject based on the ideXlab platform.
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design synthesis in silico and in vitro screening of 1 2 4 thiadiazole analogues as non peptide inhibitors of Beta Secretase
Bioorganic Chemistry, 2014Co-Authors: Archana S Gurjar, Vincenza Andrisano, Angela De Simone, Vinay VelingkarAbstract:Abstract Beta-Secretase is the key enzyme involved in Alzheimer’s disease thus; inhibition of the enzyme can lead to a potential anti-Alzheimer drug. In the search of an effective lead candidate, we have designed non-peptide inhibitor molecules based on amino aromatic heterocyclic motifs specifically, substituted 1,2,4-thiadiazole analogues. In silico modelling was employed to study interaction of the designed ligands in the enzyme active site using molecular docking approach as well as for Absorption, Distribution, Metabolism and Excretion studies. The synthesized analogues were pharmacologically screened using in vitro FRET technique. Overall results indicate that one of the analogues, compound 8 is the most promising one against Beta Secretase.
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Liquid chromatographic enzymatic studies with on-line Beta-Secretase immobilized enzyme reactor and 4-(4-dimethylaminophenylazo) benzoic acid/5-[(2-aminoethyl) amino] naphthalene-1-sulfonic acid peptide as fluorogenic substrate.
Journal of chromatography. B Analytical technologies in the biomedical and life sciences, 2014Co-Authors: Angela De Simone, Claudia Seidl, Cid Aimbiré M Santos, Vincenza AndrisanoAbstract:High throughput screening (HTS) techniques are required for the fast hit inhibitors selection in the early discovery process. However, in Beta-Secretase (BACE1) inhibitors screening campaign, the most frequently used methoxycoumarin based peptide substrate (M-2420) is not widely applicable when aromatic or heterocycle compounds of natural source show auto-fluorescence interferences. Here, in order to overcome these drawbacks, we propose the use of a highly selective 4-(4-dimethylaminophenylazo)benzoic acid/5-[(2-aminoethyl)amino]naphthalene-1-sulfonic acid (DABCYL/1,5-EDANS) based peptide substrate (Substrate IV), whose cleavage product is devoid of spectroscopic interference. HrBACE1-IMER was prepared and characterized in terms of units of immobilised hrBACE1. BACE1 catalyzed Substrate IV cleavage was on-line kinetically characterized in terms of KM and vmax, in a classical Michaelis and Menten study. The on-line kinetic constants were found consistent with those obtained with the in solution fluorescence resonance energy transfer (FRET) standard method. In order to further validate the use of Substrate IV for inhibition studies, the inhibitory potency of the well-known BACE1 peptide InhibitorIV (IC50: 0.19±0.02μM) and of the natural compound Uleine (IC50: 0.57±0.05) were determined in the optimized on-line hrBACE1-IMER. The IC50 values on the hrBACE1-IMER system were found in agreement with that obtained by the conventional methods confirming the applicability of Substrate IV for on-line BACE1 kinetic and inhibition studies.
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multiwell fluorometric and colorimetric microassays for the evaluation of Beta Secretase bace 1 inhibitors
Analytical and Bioanalytical Chemistry, 2007Co-Authors: Francesca Mancini, Marina Naldi, V Cavrini, Vincenza AndrisanoAbstract:The amyloid Beta (ABeta) peptide is responsible for toxic amyloid plaque formation and is central to the aetiology of Alzheimer’s disease (AD). It is generated by proteolytic processing of the amyloid precursor protein (APP) by Beta-Secretase (BACE-1) and gamma-Secretase. Consequently, inhibition of BACE-1, a rate-limiting enzyme in the production of ABeta, is an attractive therapeutic approach to the treatment of Alzheimer’s disease. This paper reports on improved microtiter plate-based fluorescence and colorimetric assays for the high-throughput screening (HTS) of BACE-1 inhibitors achieved by employing, for the first time, casein fluorescein isothiocyanate (casein-FITC) and N-α-benzoyl-D,L-arginine p-nitroanilide (BAPNA) as substrates, since they are known to be readily available and convenient substrates for proteases. The methods are based on the fluorescence enhancement following casein-FITC proteolysis and the visible absorbance of the p-nitroaniline (pNA) produced by BAPNA hydrolysis, with both reactions catalysed by BACE-1. Casein-FITC is a high-affinity substrate (Km = 110 nM) for BACE-1, more so than the Swedish (SW) type peptide (a peptide containing the Swedish mutant of APP, a familiar mutation that enhances ABeta production). BACE-1 catalysis of casein-FITC proteolysis exhibited Michaelis–Menten kinetic. Therefore, it was found that BACE-1 was saturable with casein-FITC that was processed in a time- and pH-dependent manner with greater catalytic efficiency than observed for the SW peptide. The enantioselective hydrolysis of L-BAPNA by BACE-1 was observed. l-BAPNA was hydrolysed ten times more efficiently by BACE-1 than the WT (wild-type peptide). The novel methods were validated using a FRET assay as an independent reference method. Therefore, in order to select new leads endowed with multifunctional activities, drugs for Alzheimer’s disease (AD)—potent acetylcholinesterase (AChE) inhibitors—were tested for BACE-1 inhibition using the proposed validated assays. Among these, donepezil, besides being an acetylcholinesterase inhibitor, was also found to be a BACE-1 inhibitor that displayed submicromolar potency (170 nM).