Brain natriuretic peptide structure

The atria and other tissues of mammals contain a family of peptides with natriuretic, diuretic, vasorelaxant, and other properties. The family includes atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and C-type natriuretic peptide (CNP). The peptides share a common 17-amino-acid disulfide ring with variable C- and N-terminals (Figure 17-5). A fourth peptide, urodilatin, has the same structure as ANP with an extension of four amino acids at the N-terminal. 

Structures of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and C-type natriuretic peptide (CNP). Sequences common to the peptides are indicated in green. 

Physiologists had postulated for a long time about the existence of a sodium excreting hormone to prevent Na overload and consequent deleterious effects of high blood pressure on the heart and vascular system. At least two such natriuretic factors have been described atrial or A-type and brain or B-type natriuretic factors. Structurally, the natriuretic factors are peptides with a cysteine-cysteine disulfide bridge creating a characteristic loop , this is illustrated by Figure 8.8. 

Quirion R, Dalpe M, De Lean A. Gutkowska J. Cantin M, Genest J. Atrial natriuretic factor (ANF) binding sites in brain and related structures. Peptides 1984 5 1167-1172. 

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