title: NMR evidence of formation of cyclocystine loops in peptide models of the high sulfur proteins from wool.
abstract: We report that in peptide models of the high sulfur proteins of the matrix from wool a disulfide bond forms between two sequential Cys-residues as a result of a simple oxidation procedure. This tiny cyclocystine loop manifests itself in many ways in 1H NMR spectra. The formation of the loop is accompanied, as expected, by conversion of the Cys-Cys peptide bond from its usual trans-configuration into the energetically less favorable cis-configuration. Possible consequences of the formation of cyclocystine loops for the elasticity of the network of the matrix are discussed.
authors.affiliation: Philadelphia College of Textiles and Science, PA 19144, USA. mark@curly.texsci.edu
authors.forename: M I
authors.initials: MI
authors.lastname: Liff
authors.forename: S S
authors.initials: SS
authors.lastname: Siddiqui
mesh_terms: D000818:Animals; D003553:Cystine / Q000031:analogs & derivatives* / Q000737:chemistry; D004220:Disulfides / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D010084:Oxidation-Reduction; D010100:Oxygen; D010446:Peptide Fragments / Q000737:chemistry; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry*; D013455:Sulfur / Q000737:chemistry*; D014867:Water; D014935:Wool / Q000737:chemistry*
chemical_list: D004220:Disulfides; D010446:Peptide Fragments; D011506:Proteins; D014867:Water; C010900:cyclocystine; D003553:Cystine; D013455:Sulfur; D010100:Oxygen