Hydrolytic Cleavage of Pyroglutamyl-peptide Bond. V. Selective Removal of Pyroglutamic Acid from Biologically Active Pyroglutamylpeptides in High Concentrations of Aqueous Methanesulfonic Acid
Application of aqueous methanesulfonic acid (MSA) for selective chemical removal of pyroglutamic acid (pGlu) residue from five biologically active pyroglutamyl-peptides (pGlu-X-peptides, X=amino acid residue at position 2) was examined. Gonadotropin releasing hormone (Gn-RH), dog neuromedin U-8 (d-NMU-8), physalaemin (PH), a bradykinin potentiating peptide (BPP-5a) and neurotensin (NT) as pGlu-X-peptides were incubated in either 70% or 90% aqueous MSA at 25 °C. HPLC analysis of the incubation solutions showed that the main decomposition product was H-X-peptide derived from each pGlu-X-peptide by the removal of pGlu. The results revealed that the pGlu-X peptide bond had higher susceptibility than various internal amide bonds in the five peptides examined, including the Trp-Ser bond in Gn-RH, the C-terminal Asn-NH2 in d-NMU-8, and the Asp-Pro bond in PH, whose acid susceptibility is well known. Thus, mild hydrolysis with high concentrations of aqueous MSA may be applicable to chemically selective removal of pGlu from pGlu-X-peptides for structural examinations.
Synthesis of LH-RH using a new phenolic polymer as solid support and “BOP” reagent for fragment coupling
作者:P. Rivaille、J.P. Gautron、B. Castro、G. Milhaud
DOI:10.1016/0040-4020(80)80193-1
日期:1980.1
p-Hydroxyphenyl propionic resin (Table I, compound 4) was used to prepare the 1–6 protected fragment of LH-RH which was then condensed with “BOP” (benzotriazolyl N-oxytrisdimethylaminophosphonium hexafluorophosphate) as couplingreagent to the 7–10 residue synthesized on the same resin. Peptidylresin was divided into two aliquots in order to obtain LH-RH after aminolysis and treatment with liquid hydrogen