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Proteomics and Protein Markers |
1 Division of Clinical Biochemistry, Innsbruck Biocenter, Innsbruck Medical University, Innsbruck, Austria; 2 Department of Medical and Chemical Laboratory Diagnostics, Innsbruck Medical University, Innsbruck, Austria; 3 Department of Internal Medicine, Clinical Division of Cardiology, Innsbruck Medical University, Innsbruck, Austria.
aAddress correspondence to this author at: Division of Clinical Biochemistry, Innsbruck, Biocenter, Innsbruck Medical University, Fritz-Pregl-Str. 3, A-6020 Innsbruck, Austria. Fax 43-512-9003-73300; e-mail herbert.lindner{at}i-med.ac.at.
Background: The specific forms of pro–B-type natriuretic peptide (proBNP) that occur in human blood are not yet clear. We demonstrated the presence of several proBNP forms in human plasma with a new affinity chromatography method that can be used in combination with nano–liquid chromatography electrospray ionization tandem mass spectrometry (nano-LC–ESI–MS/MS).
Methods: For affinity chromatography, we coupled Fab' fragments of polyclonal sheep antibodies specific for N-terminal proBNP (NT-proBNP) epitope 1–21 to silica beads. We connected a column (10 mm x 0.8 mm inner diameter) packed with these beads to a trypsin reactor and used a preconcentrator in combination with a fritless nanospray column to perform MS analyses of proBNP forms in preextracted and non-preextracted samples of plasma from patients with severe heart failure (HF). We used Western blotting in deglycosylation experiments to confirm the shifts in proBNP and NT-proBNP masses.
Results: Tandem MS experiments demonstrated the presence of both NT-proBNP and circulating proBNP in preextracted samples of plasma from patients with severe HF, and Western blotting analyses revealed 2 bands of approximately 23 kDa and 13 kDa that shifted after deglycosylation to positions that corresponded to the locations of recombinant proBNP and synthetic NT-proBNP.
Conclusions: We obtained clear evidence for circulating proBNP in patients with severe HF and provided the first demonstration of O-glycosylation of NT-proBNP. The higher molecular masses for NT-proBNP and proBNP observed in the Western blotting analyses than those expected from calculations can be explained by O-glycosylation of these peptides in vivo.
The following articles in journals at HighWire Press have cited this article:
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L. Frankenstein, A. Remppis, M. Nelles, B. Schaelling, D. Schellberg, H. Katus, and C. Zugck Relation of N-terminal pro-brain natriuretic peptide levels and their prognostic power in chronic stable heart failure to obesity status Eur. Heart J., November 1, 2008; 29(21): 2634 - 2640. [Abstract] [Full Text] [PDF] |
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