Molecular forms of human brain natriuretic peptide in plasma

Abstract

Background: Brain natriuretic peptide (BNP) is a vasoreactive peptide hormone, which is synthesized and secreted mainly from the heart ventricles. Methods: Molecular forms of immunoreactive human brain natriuretic peptide (BNP) were examined. Chemically synthesized human BNP was added to whole blood samples from a healthy volunteer. The immunoreactive peptide was recovered by immunoaffinity chromatography followed by reversed-phase HPLC (RP-HPLC). Molecular form of immunoreactive BNP in plasma from heart failure patients was also examined. Results: Sequential analysis and amino acid analysis of the peptide revealed that two amino acid residues were deleted from the amino terminus of BNP. When roughly classified according to molecular weight (MW), two forms of BNP (high-MW BNP and low-MW BNP) were observed. The estimated MW of high-MW BNP (36 kDa) was three times that of pro-BNP (12 kDa). Conclusions: Analysis of low-MW BNP by RP-HPLC revealed that a small amount of BNP 1–32 or des-SerPro-BNP (BNP 3–32) was contained in plasma from heart failure patients.