Optimization of the Synthesis of an Apelin-12 Structural Analog and the NMR Study of Its Stability in Human Plasma

A method for the solid-phase synthesis of the apelin-12 analog has been developed using the Fmoc methodology in combination with the temporary protection of the guanidine function of the arginine residues by protonation (salt formation) during the formation of the amide bond. Proton magnetic resonance spectroscopy has been used to compare the proteolytic stability of apelin-12 and its structural analog in human blood plasma. The half-life of the analog in plasma has been shown to be about three times longer than that of the natural peptide.