ALZHEIMER'S AMYLOID BETA AND APOLIPOPROTEINS OF THE CSF: MASS SPECTROMETRY STUDY
A.R. Koudinov1,2*, R. Beavis3, T.T. Berezov1 and N.V. Koudinova1,2
1. Russian Academy of Medical Sciences, National Mental Health Research Center, Institute of Biomedical Chemistry, Timoshenko 38-27, Moscow 121359, Russian Federation
2. Department of Neurobioliology, Weizmann Institute, Rehovot 76100, Israel
3. Department of Pharmacology, New York University Medical Center, 560 First Avenue, New York, NY 10016, USA
In normal human plasma and CSF the soluble amyloid beta protein (sAb) is associated with the HDL. The present work had the aim of characterization of sAb and apolipoproteins (apo) of CSF HDL by mass-spectrometry. To this end HDL were first obtained by sequential flotation ultracentrifugation of the CSF and the sAb and apos were further fractionated by reverse phase HPLC on a C4 analytical column over the linear gradient of 20 to 80% acetonitrile in 0.1% TFA. The sAb and apo fractions obtained were characterized then by SDS/PAGE, immunoblot analysis with different antibodies and by matrix-assisted laser desorption/ionization mass spectrometry ( MALDI MS, Table ). In addition to MALDI-MS listed in the Table apos were characterized by amino-acid sequence analysis while apoC-II was detected by immunoblotting with anti-apoC-II specific antibodies. Soluble Ab had intact N-terminus and no minor N-terminal heterogeneity. Our data i) suggest that the major sAb specie of the CSF-HDL is Ab1-40 and ii) characterize CSF apos.
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