title: Urea-based two-dimensional electrophoresis of beta-amyloid peptides in human plasma: evidence for novel Abeta species.
abstract: The detailed analysis of beta-amyloid (Abeta) peptides in human plasma is still hampered by the limited sensitivity of available mass spectrometric methods and the lack of appropiate ELISAs to measure Abeta peptides other than Abeta(1-38), Abeta(1-40), and Abeta(1-42). By combining high-yield Abeta immuno- precipitation (IP), IEF, and urea-based Abeta-SDS-PAGE-immunoblot, at least 30 Abeta-immuno-reactive spots were detected in human plasma samples as small as 1.6 mL. This approach clearly resolved Abeta peptides Abeta(1-40), Abeta(1-42), Abeta(1-37), Abeta(1-38), Abeta(1-39), the N-truncated Abeta(2-40), Abeta(2-42), and, for the first time, also Abeta(1-41). Relative quantification indicated that Abeta(1-40) and Abeta(1-42) accounted for less than 60% of the total amount of Abeta peptides in plasma. All other Abeta peptides appear to be either C-terminally or N-terminally truncated forms or as yet uncharacterized Abeta species which migrated as trains of spots with distinct pIs. The Abeta pattern found in cerebrospinal fluid (CSF) was substantially less complex. This sensitive method (2-D Abeta-WIB) might help clarifying the origin of distinct Abeta species from different tissues, cell types, or intracellular pools as well as their amyloidogenicity. It might further help identifying plasma Abeta species suitable as biomarkers for the diagnosis of Alzheimer's disease (AD).
authors.affiliation: Department of Psychiatry and Psychotherapy, University of Erlangen-Nuremberg, Erlangen, Germany.
authors.forename: Juan Manuel
authors.initials: JM
authors.lastname: Maler
authors.forename: Hans-Wolfgang
authors.initials: HW
authors.lastname: Klafki
authors.forename: Sabine
authors.initials: S
authors.lastname: Paul
authors.forename: Philipp
authors.initials: P
authors.lastname: Spitzer
authors.forename: Teja Wolfgang
authors.initials: TW
authors.lastname: Groemer
authors.forename: Andreas Wolfram
authors.initials: AW
authors.lastname: Henkel
authors.forename: Hermann
authors.initials: H
authors.lastname: Esselmann
authors.forename: Piotr
authors.initials: P
authors.lastname: Lewczuk
authors.forename: Johannes
authors.initials: J
authors.lastname: Kornhuber
authors.forename: Jens
authors.initials: J
authors.lastname: Wiltfang
mesh_terms: D000544:Alzheimer Disease / Q000097:blood; D016229:Amyloid beta-Peptides / Q000097:blood* / Q000737:chemistry*; D015180:Electrophoresis, Gel, Two-Dimensional; D006801:Humans; D008875:Middle Aged; D010446:Peptide Fragments / Q000097:blood* / Q000737:chemistry*; D014508:Urea
chemical_list: D016229:Amyloid beta-Peptides; D010446:Peptide Fragments; C078639:amyloid beta-protein (1-38); C075222:amyloid beta-protein (1-42); D014508:Urea