Analysis of circulating forms of proBNP and NT-proBNP in patients with severe heart failure

作者：Hammerer Lercher Angelika; Halfinger Bernhard; Sarg Bettina; Mair Johannes; Puschendorf Bernd; Griesmacher Andrea; Guzman Norberto A; Lindner Herbert H^*

来源：Clinical Chemistry, 2008, 54(5): 858-865.

DOI：10.1373/clinchem.2007.090266

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 NIS 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.

• 出版日期2008-5