title: Structural study of electrolysis-induced degradation of the growth hormone releasing peptide His-D-Trp-Ala-Trp-D-Phe-Lys-NH2.
abstract: Growth hormone releasing peptide (GHRP, sequence His-D-Trp-Ala-Trp-D-Phe-Lys-NH2) is a synthetic hexapeptide under consideration for transdermal iontophoretic drug delivery. Cyclic voltammetry, controlled-potential electrolysis, HPLC/UV analysis, LC/MS/MS analysis, and EPR spin-trapping studies indicate that the electrolysis-induced oxidative degradation of GHRP is likely to be mediated by electrogenerated oxygen radicals from the electrolysis of water. Within 2 h and up to 2.5 V versus an Ag/AgCl reference electrode, the peptide backbone remains largely intact. The chemical modifications are selectively on imidazole (histidine) and indole (tryptophan). Strategies for alleviating the electrolysis-induced degradation of GHRP are proposed.
authors.affiliation: Physical and Structural Chemistry Department, SmithKline Beecham Pharmaceuticals, King of Prussia, Pennsylvania 19406, USA.
authors.forename: H Y
authors.initials: HY
authors.lastname: Cheng
authors.forename: L L
authors.initials: LL
authors.lastname: Davis
authors.forename: M J
authors.initials: MJ
authors.lastname: Huddleston
authors.forename: S A
authors.initials: SA
authors.lastname: Carr
mesh_terms: D000595:Amino Acid Sequence; D004572:Electrolysis; D004578:Electron Spin Resonance Spectroscopy; D013007:Growth Hormone-Releasing Hormone / Q000737:chemistry*; D013058:Mass Spectrometry; D008969:Molecular Sequence Data
chemical_list: D013007:Growth Hormone-Releasing Hormone