INVESTIGATION OF CRUDES OF SYNTHESIS OF NEUROPEPTIDE-Y BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY ELECTROSPRAY MASS-SPECTROMETRY

Neuropeptide Y (NPY) and its modified form, [Leu(31), Pro(34)]NPY, are both thirty six amino acids long and they have relative molecular mas ses of 4250 and 4220. Solid-phase synthesis of both peptides resulted in complex crudes of reaction, which were investigated by means of com bined high-performance liquid chromatography-electrospray mass spectro metry (HPLC-ES-MS). The combination of these two powerful analytical t echniques allowed rapid and reliable identification of the target pept ides and furnished comprehensive information on other reaction product s, which were mainly peptidic chains containing a smaller number of am ino acids compared to those present in the intact peptides. The possib le origin of such side-products and the eventual purification and unam biguous identification of both peptides are discussed.