FEATURES OF MASS SPECTROMETRIC DETECTION BETA OF AMYLOID PEPTIDES (ALZHEIMER'S PEPTIDES)

Mass spectrometry combined with the use of isotope-labeled standards is one of the favored methods for the quantitative measurement of beta-amyloid concentrations in biological media. This article is devoted to the prevention of typical systematic errors in such measurements arising from the neglect of the possibility of betaamyloid transformation into the denatured form, which gives in mass spectra signals three times more intensity than the native form. The degree of this denaturation was determined by the ability of the native form to set up a complex with α-2-macroglobulin. The denatured form lacks this point. It was shown that denaturation can occur in the case of heat treatment in an acidic environment or when DMSO is used as a solvent. Measurement error occurs when the isotope-labeled standard and the analyte are of different forms. There are suggested recommendations to overcome systematic errors in the quantitative analysis of these compounds by forcing denaturation of the mixture of the analyte with the standard before analysis.