A Novel Screening Platform For Inhibitors Based On ICP-MS And BACE1 Inhibitors

Alzheimer’s disease(AD)was first discovered and reported by the German psychiatrist Alosis Alzheimer in 1907.It is a common neurodegenerative disease in the elderly.Its pathological features are neurofibrillary tangles and senile plaques,which are associated with tau hyperphosphorylation and Aβ accumulation,respectively.There are many pathogenesis of Alzheimer’s disease.The most common pathogenesis is the amyloid cascade hypothesis,which states that there are two processes for the hydrolysis of amyloid precursor protein(APP),outside the cell membrane.α-Secretase hydrolysis releases a soluble N-terminal product,the α-APPs and C83 fragment polypeptides.C83 can also produce P3(Aβ17-40 and Aβ17-42)byγ-secretase.The two fragments produced do not contain intact Aβ and do not have the ability to form amyloid deposits.This process is non-amyloid precipitation pathway;β-secretase acts on APP to produce β-APPs and C99 fragment polypeptides on the cell membrane,and C99 is hydrolyzed into different lengths of Aβ(1～40)and Aβ(1～42)by γ-secretase.The process is an amyloid precipitation pathway.According to this hypothesis,β-secretase is the rate-limiting enzyme that produces Aβ.Sinceα-secretase and γ-secretase are involved in many important physiological processes,promoion or inhibition of them might result in side effects.In mice whose β-secretase gene were knocked out,the physiological process was not affected,so β-secretase was used as an important target for AD treatment.On the basis of the results of comprehensive analysis of the literature,this thesis selects a weak β-secretase inhibitor with guanidyl structure as the core structure(No.Ⅰ in this paper)as a lead compound,and its structure is modified to obtain new inhibitors with a strong inhibitory effect.On the basis of the analysis of the lead compound and β-secretase active site,we designed two compounds Ⅱ and Ⅲ,and computer-assisted simulation results showed that the inhibitory effect increased.Common β-secretase screening platforms are based on fluorescence energy resonance transfer(FRET)and surface plasmon resonance(SPR)technologies.FRET has the advantages of high sensitivity,ease of use,and ability of imaging.However,its disadvantage is that the presence of organic fluorescent groups reduces the solubility of the polypeptide,reduces the efficiency of cutting,and affects by autofluorescene from biological background interference,which may cause false positive results.The advantages of SPR are high sensitivity,high throughput,miniaturization,and its disadvantages is that it is difficult to distinguish non-specific adsorption,and it is very sensitive to interference factors such as temperature and sample composition.The ICPMS screening platform we designed can overcome the interference of biological background,and has the advantages of high sensitivity and accuracy.