Urea-based two-dimensional electrophoresis of beta-amyloid peptides in human plasma: evidence for novel Abeta species.
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).
Maler
Juan Manuel
JM
Department of Psychiatry and Psychotherapy, University of Erlangen-Nuremberg, Erlangen, Germany.
Klafki
Hans-Wolfgang
HW
Paul
Sabine
S
Spitzer
Philipp
P
Groemer
Teja Wolfgang
TW
Henkel
Andreas Wolfram
AW
Esselmann
Hermann
H
Lewczuk
Piotr
P
Kornhuber
Johannes
J
Wiltfang
Jens
J
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
D016229:Amyloid beta-Peptides; D010446:Peptide Fragments; C078639:amyloid beta-protein (1-38); C075222:amyloid beta-protein (1-42); D014508:Urea