Both synthetic and endogenous $A{\beta}$ are degraded by peptidase G. Both $A{\beta}40$ and 42 are cleaved by peptidase G. Peptidase G cleaves $A{\beta}40$ into small fragments ($A{\beta}18$) which lacks aggregation property and are not toxic to neuron. Peptidase G seems to degrade multimeric $A{\beta}$ more efficiently than monomeric $A{\beta}$. Peptidase G protects neurons from toxicity induced by $A{\beta}$ by cleaving it into smaller fragments. Thus, dis-regulation of peptidase G could contribute amyloid deposit found in AD brain.

P25/CDK5 phosphorylates BACE1. 2. P25 is a new target for AD therapeutics. 3. P25 inhibitors should block both $A{\beta}$ pathway and Tau pathway.

Amyloid beta ($A{\beta}$) is believed one of the major pathogens of Alzheimer's disease (AD), and the reduction of $A{\beta}$ is considered a primary therapeutic target. Immunization with $A{\beta}$ can reduce $A{\beta}$ burden and pathological features in transgenic AD model mouse. This means $anti-A{\beta}$ autoantibodies may have a role in AD pathology. Recent findings suggest $anti-A{\beta}$ autoantibodies level decrease in AD patients. The early detection of AD is important for treatment of this disease. However, diagnosis on AD has only been possible through limited methods such as neuropsychological examination or MRI. To investigate whether it was possible to detect the presence and different levels of naturally occurring $anti-A{\beta}$ autoantibodies in the plasma of patients with AD and age-matched controls. An advanced ELISA was performed to detect levels of naturally occurring $anti-A{\beta}$ autoantibodies in the plasma. The level of $anti-A{\beta}$ auto-antibodies from patients with idiopathic Parkinson's disease or stroke and from normal controls were compared to that of AD patients. Our results showed a significantly lower $anti-A{\beta}$ autoantibodies level in AD compared to those with other neurological diseases or control. The level of $anti-A{\beta}$ autoantibodies in the serum may be used to diagnose the presence of AD.