title: New potent hGH-RH analogues with increased resistance to enzymatic degradation.
abstract: Four hGH-RH analogues containing homoarginine (Har) and/or D-Arg were obtained by solid-phase methodology using Boc-chemistry. To introduce Har residues, a Lys(Fmoc) protected Lys derivative was incorporated in the appropriate positions (11, 12, 20, 21 or 29): after assembly of the peptide chain the Fmoc group was removed and the peptide-resin was guanidinylated by treatment with N,N'-bis(tert-butoxycarbonyl)-S-methylisothiourea. The peptides were cleaved from the resin by treatment with liquid HF, and the products were purified by RP-HPLC. The peptides were subjected to digestion by trypsin, and the course of the reaction was followed by HPLC and ESI-MS. It was found that peptide bonds formed by the carboxyl group of Har are completely stable to trypsin. The course of cleavage at Lys or Arg residues depends on the position of Har in the sequence. All the analogues investigated stimulate the release of GH in rats after subcutaneous administration, and were about 50-100 times as potent as rGH-RH itself. The analogues had no effect on PRL, LH and FSH levels.
authors.affiliation: Laboratory of Peptides, Warsaw University, Poland. izdebski@chem.uw.edu.pl
authors.forename: Jan
authors.initials: J
authors.lastname: Izdebski
authors.forename: Ewa
authors.initials: E
authors.lastname: Witkowska
authors.forename: Danuta
authors.initials: D
authors.lastname: Kunce
authors.forename: Alicja
authors.initials: A
authors.lastname: Orłowska
authors.forename: Bogusława
authors.initials: B
authors.lastname: Baranowska
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Radzikowska
authors.forename: Marek
authors.initials: M
authors.lastname: Smoluch
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001774:Blood Chemical Analysis; D002851:Chromatography, High Pressure Liquid; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D019791:Guanidine / Q000378:metabolism; D019382:Human Growth Hormone / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D007986:Luteinizing Hormone / Q000097:blood; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D011388:Prolactin / Q000097:blood; D051381:Rats; D011921:Rats, Inbred WKY; D021241:Spectrometry, Mass, Electrospray Ionization; D013997:Time Factors; D014357:Trypsin / Q000378:metabolism*
chemical_list: D010446:Peptide Fragments; D019382:Human Growth Hormone; D011388:Prolactin; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D014357:Trypsin; D019791:Guanidine