title: Des-Nalpha-acetyl-alpha-melanotropin: a synthetic substrate for specific N-terminal directed enzymatic acetylation.
abstract: Application of the 2-methylsulfonylethyloxycarbonyl group for temporary amino protection enables the synthesis from one precursor of des-Nalpha1-acetyl-alpha-MSH, the two mono N-acetylated forms (in positions I and II) and the diacetyl form of this tridecapeptide amideq The free tridecapeptide amide, although structurally unrelated to the normal substrate, was recognized by an enzyme occurring in calf eye-lens tissue. The product of the enzymatic reaction was exclusively alpha-MSH. Partial sequences derived from the N-terminus were less rapidly acetylated or not at all, depending on their chain length. The enzyme, therefore, appears to direct its activity to free N-terminal alpha-amino groups of peptides exceeding a certain critical chain length. Acetylation of epsilon-amino functions did not occur.
mesh_terms: D000107:Acetylation; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002417:Cattle; D055598:Chemical Phenomena; D002621:Chemistry; D007908:Lens, Crystalline / Q000201:enzymology; D009074:Melanocyte-Stimulating Hormones / Q000031:analogs & derivatives* / Q000032:analysis / Q000138:chemical synthesis
chemical_list: D000596:Amino Acids; D009074:Melanocyte-Stimulating Hormones