The article by Kazuhiro Tateimoto reports the complete amino acid sequence of neuropeptide Y (NPY), a 36-residue peptide isolated from porcine brain. The sequence was determined using high-performance liquid chromatography (HPLC) to separate tryptic and chymotryptic fragments, followed by an improved dansyl Edman subtractive technique for sequence analysis. The sequence of NPY is highly homologous to peptide YY (76%) and pancreatic polypeptide (50%), suggesting that they form a new peptide family. The study also describes a modified dansyl Edman procedure that includes a subtractive step to confirm sequence results and monitor the Edman reaction cycle. The biological activities of NPY, similar to those of PYY and PP, include inhibiting secretin-stimulated pancreatic secretion and exhibiting vasoconstrictor properties. The findings highlight the structural and functional similarities among these peptides, suggesting they may share a common evolutionary origin.The article by Kazuhiro Tateimoto reports the complete amino acid sequence of neuropeptide Y (NPY), a 36-residue peptide isolated from porcine brain. The sequence was determined using high-performance liquid chromatography (HPLC) to separate tryptic and chymotryptic fragments, followed by an improved dansyl Edman subtractive technique for sequence analysis. The sequence of NPY is highly homologous to peptide YY (76%) and pancreatic polypeptide (50%), suggesting that they form a new peptide family. The study also describes a modified dansyl Edman procedure that includes a subtractive step to confirm sequence results and monitor the Edman reaction cycle. The biological activities of NPY, similar to those of PYY and PP, include inhibiting secretin-stimulated pancreatic secretion and exhibiting vasoconstrictor properties. The findings highlight the structural and functional similarities among these peptides, suggesting they may share a common evolutionary origin.