Delta sleep-inducing peptide (DSIP) is a naturally occurring nonapeptide — a chain of nine amino acids — with the sequence Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu. It has a molecular weight of 848.81 g/mol and the formula C₃₅H₄₈N₁₀O₁₅ (CAS 62568-57-4). First isolated in 1977 from rabbit cerebral venous blood, DSIP is classified as amphiphilic, meaning it contains both water-attracting and water-repelling regions. The tryptophan residue at its N-terminus provides a characteristic UV absorbance signature used for laboratory identification. DSIP is a low-molecular-weight amphiphilic nonapeptide — the selective membrane that separates circulating blood from brain tissue. It appears as a white lyophilized powder that is soluble in water. This product is strictly for research purposes only.