Estimation of phosphorylation level of amyloid-beta isolated from human blood plasma: Ultrahigh-resolution mass spectrometry

Recently, amyloid-beta (A beta) phosphorylation at position 8 has been shown to be associated with pathogenesis of Alzheimer's disease. Since the modification occurs in the key fragment of the metal-binding domain of A beta and should seriously affect the interaction of pS8-A beta with zinc ions, this isoform may be a potential precursor of pathogenic oligomer forms of A beta. Hence the level of pS8-A beta in human biological fluids (blood, urine, cerebrospinal fluid) may reflect various stages of pathogenesis of the Alzheimer's disease. The aim of the work was to develop a prototype of an analytical method for quantitative determination of the level of pS8-A beta isoform in binary mixtures with native A beta in order to further use it to estimate the levels of phosphorylated amyloid-beta in blood plasma samples of patients diagnosed with Alzheimer's disease.