In Vitro Molecular Structure of N-Terminal B-Type Natriuretic Peptide: Monomer or Oligomer?

Abstract

To the Editor: In the circulation, the A-type natriuretic peptide and the B-type natriuretic peptide (BNP) regulate cardiovascular homeostasis. Each hormone is derived from biosynthetic precursors that are processed to the active C-terminal hormones and the N-terminal fragments (1). Measurements of both BNP and N-terminal proBNP in plasma are recommended as diagnostic tools for heart failure. The peptides are measured by immunoassays that use antibodies directed against specific epitopes. A basic understanding of the native peptide structure in terms of posttranslational modifications is thus paramount, because changes in posttranslational processing will affect assay measurement and clinical interpretation drastically. A recent report in Clinical Chemistry addressed the possibility of natriuretic peptide oligomerization in a study that used a recombinant N-terminal proBNP peptide (possessing a glycine–serine N-terminal extension) spiked into 3 matrices (2). Buffer, plasma, or serum was incubated for various times and temperatures; the material was then applied to a reversed-phase column, a gel-filtration column, and a reversed-phase column, respectively. All 3 columns were eluted with …