A new strategy for metabolic stabilization of motilin using the C-terminal part of ghrelin

• Published in: Peptides (New York, N.Y. : 1980) Vol. 33; no. 2; pp. 279 - 284
• Main Authors: Morozumi, Naomi, Sato, Seiji, Yoshida, Sayaka, Yamaki, Akira, Furuya, Mayumi, Inomata, Norio, Ohnuma, Norio, Minamitake, Yoshiharu, Ohsuye, Kazuhiro, Kangawa, Kenji
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.02.2012
• Subjects: agonists; Amino Acid Motifs; Amino Acid Sequence; Amino acids; Animals; Binding; bioactive properties; Biological; Biotransformation; Chimeric peptide; chimerism; CHO Cells; Cricetinae; esterases; Fragmentation; G-protein coupled receptors; Ghrelin; Ghrelin - chemistry; Ghrelin - pharmacokinetics; Ghrelin - pharmacology; glutamic acid; Half-Life; Humans; Male; Metabolic stability; Molecular Sequence Data; Motilin; Motilin - chemistry; Motilin - pharmacokinetics; Motilin - pharmacology; motilin receptors; Peptide Fragments - chemistry; Peptide Fragments - pharmacokinetics; Peptide Fragments - pharmacology; Peptides; Pharmacokinetics; Protein Stability; Rats; Rats, Sprague-Dawley; Receptors; Receptors, Gastrointestinal Hormone - agonists; Receptors, Neuropeptide - agonists; Recombinant Fusion Proteins - chemistry; Recombinant Fusion Proteins - pharmacokinetics; Recombinant Fusion Proteins - pharmacology; Residues; serine; Surgical implants; Terminal half-life in plasma; GPR38; GH; [Ca2+]i; T1/2; ip; Motilin; RIA; iv; Chimeric peptide; SD; Metabolic stability; Terminal half-life in plasma; Ghrelin; GHS-R1a; EC50; PK; Pharmacokinetics
• ISSN: 0196-9781; 1873-5169
• DOI: 10.1016/j.peptides.2012.01.010

► The C-terminal(8–28) part of ghrelin is important in the biological activity in vivo. ► Motilin is degraded very rapidly in plasma. ► Motilin(1–12) and ghrelin(12–28) chimeric peptide has an equipotent motilin agonist activity. ► Motilin(1–12) and ghrelin(12–28) chimeric peptide is more stable in vivo than motilin. ► The C-terminal part of ghrelin has a potential to improve the biokinetics of motilin. Ghrelin consists of 28 amino acid residues with an octanoyl modification at the third serine residue. Recently we have found that the C-terminal part of ghrelin protects the ester bond of 3-octanoyled serine from plasma esterases and plays the essential role to prolong the plasma half-life and to show its biological activity in vivo. In the present study, we researched whether the C-terminal part of ghrelin has a potential to prolong the plasma half-life of motilin, by comparing the pharmacokinetics of various chimeric peptides of ghrelin and motilin. Motilin is another gastro-intestinal peptide hormone related with ghrelin structurally, binding to the same family of G protein-coupled receptors. Chimeric peptides were designed to be composed of motilin(1–12) fragment, the active core binding to the motilin receptor, GPR38, and C-terminal part of ghrelin. The modification of motilin(1–12) fragment by C-terminal part of ghrelin hardly influenced its agonist activity to GPR38 and almost all these chimeric peptides showed more than two times longer plasma half-lives than motilin in rats. From the relationship between structures of chimeric peptides and their corresponding plasma half-lives, the mid-region of ghrelin rich in basic amino acids (15RKESKK20) was considered to be the most important in prolonging the plasma half-life of motilin. The deletion of these fragments or replacement of 17th glutamic acid with a neutral amino acid resulted in short plasma half-lives. In conclusion, our data suggested that the C-terminal part of ghrelin has a potential to improve the biokinetics of motilin probably by a metabolic stabilizing effect.