title: Bioactive peptides: conformational study of a cystinyl cycloheptapeptide in its free and calcium complexed forms.
abstract: The disulphide bridged heptapeptide Boc-Cys-Val-Pro-Pro-Phe-Phe-Cys-OMe has been synthesized by classical solution methods. An ion binding study showed the peptide's ability to complex calcium ions with definite stoichiometry. The solution conformation of the peptide in its free and calcium-complexed form has been investigated by CD and nmr. The model structure derived from nmr data has been energy minimized and the resulting structure investigated by molecular dynamics simulation in water. The structure of the equimolar peptide/Ca2+ complex in acetonitrile at room temperature shows the presence of two transannular hydrogen bonds, with the formation of two ring structures of the C10 (type VIa) and C14 type. One peptide unit (Pro-Pro) is cis, all others are trans.
authors.affiliation: Centro di Studi Chimica del Farmaco del CNR, Roma, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Zanotti
authors.forename: A
authors.initials: A
authors.lastname: Maione
authors.forename: F
authors.initials: F
authors.lastname: Rossi
authors.forename: M
authors.initials: M
authors.lastname: Saviano
authors.forename: C
authors.initials: C
authors.lastname: Pedone
authors.forename: T
authors.initials: T
authors.lastname: Tancredi
mesh_terms: D000097:Acetonitriles; D000595:Amino Acid Sequence; D002118:Calcium / Q000378:metabolism*; D003198:Computer Simulation; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010456:Peptides, Cyclic / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D011487:Protein Conformation; D012996:Solutions; D012997:Solvents; D014867:Water
chemical_list: D000097:Acetonitriles; D010456:Peptides, Cyclic; D012996:Solutions; D012997:Solvents; D014867:Water; C082474:CYS7; D002118:Calcium; C032159:acetonitrile