The main structure of BNP in human plasma is a 32 peptide containing a specific ring structure, which has an intramolecular disulfide bond connecting two cysteines and containing 17 amino acid residues. The activity of BNP is particularly dependent on its circular central structure. The human BNP gene is located at the end of the short arm of chromosome 1 and contains three exons and two introns. BNP gene can be transcribed into 1900 nucleotides of DNA complementary chain (cDNA), so as to synthesize mRNA, and then explosive translation into 134 amino acid composition of pre-proBNP, the peptide under the action of protease rapidly decomposed into a 26 amino acid signal peptide and containing 108 amino acid peptide proBNP. Subsequently, proBNP is decomposed by type Ⅱ transmembrane serine protease into an inactive 76 amino acid peptide (the N terminal of the precursor of cerebral natriuretic peptide) and a 32 amino acid peptide BNP with endocrine activity. pre-proBNP and pro-BNP formed after expression in the above process are unstable and quickly decomposed. BNP is relatively stable, and is completely released into the blood, with a high concentration and a long half-life, so BNP is often detected in clinical application. A large number of clinical studies have confirmed that BNP is a sensitive indicator of impaired cardiac function. BNP is synthesized, secreted and released under the stimulation of myocardial ischemia, necrosis, injury, ventricular wall tension and pressure overload, and has the effects of sodium, drainage and vascular dilation. Because the nucleic acid sequence of BNP contains the unstable TATTTAT sequence, its mRNA conversion is fast, so that BNP can be synthesized instantaneously, directly proportional to reflect the ventricular capacity and pressure overload, so it can reflect the degree of ventricular dysfunction more sensitive and specific, and is closely related to the severity of heart failure.
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