title: Conformational analysis of cyclo(2,9)-Ac-QCRSVEGSCG-OH from the C-terminal loop of human growth hormone.
abstract: A 10 amino acid residue cyclic peptide, cyclo(2,9)-Ac-Gln1-Cys2-Arg3-Ser4-Val5-Glu6-Gly7 -Ser8-Cys9-Gly10, from the C-terminal region of human growth hormone (hGH) was synthesized and studied by 2D proton NMR and molecular dynamics (MD) simulations. The solubility of the peptide was low in water; hence, NMR studies were done in two solvent mixtures, water and deuterated dimethyl sulfoxide. NOE-constrained molecular dynamics and MD simulations resulted in major and minor conformers in solution. The major conformer has a type I beta-turn at Gln1-Cys2-Arg3-Ser4 and a loop structure around Glu6-Gly7-Ser8. Comparison of the conformation of this peptide with the peptide fragment 181-190 in the intact hGH protein X-ray crystal structure indicated that the synthetic peptide retains some structural similarity to the intact protein. Since the C-terminal region is important in binding the hGH protein to its receptor, the conformation of the synthetic peptide could be useful in understanding the binding mechanism.
authors.affiliation: Department of Pharmaceutical Chemistry, University of Kansas, lawrence, USA.
authors.forename: D S
authors.initials: DS
authors.lastname: Jois
authors.forename: M W
authors.initials: MW
authors.lastname: Conrad
authors.forename: S
authors.initials: S
authors.lastname: Chakrabarti
authors.forename: T J
authors.initials: TJ
authors.lastname: Siahaan
mesh_terms: D000595:Amino Acid Sequence; D019382:Human Growth Hormone / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D010456:Peptides, Cyclic / Q000737:chemistry*; D011487:Protein Conformation
chemical_list: D010456:Peptides, Cyclic; C106658:cyclo(2,9)(acetyl-glutaminyl-cysteinyl-arginyl-seryl-valyl-glutamyl-glycyl-seryl-cysteinyl-glycyl); D019382:Human Growth Hormone