title: Biradicals as ESR probes of conformations in model beta-turn peptides.
abstract: Electron spin-spin exchange interaction in biradicals has been examined for its potential usefulness in the conformational analysis of peptides in solution. Three peptides with high propensity to adopt beta-turn conformations in solution, Boc-Cys-Pro-Xxx-Cys-NHMe (Xxx = Leu, 1; Xxx = Aib, 2; Xxx = Tyr, 3), have been modified into biradicals by spin labeling the thiols groups. Analysis of electron spin resonance spectra of these peptides in a variety of solvents and at different temperatures suggests that the population of folded conformations follows the order 2 > 1 > 3.
authors.affiliation: Department of Chemistry, Indian Institute of Technology, Madras.
authors.forename: S
authors.initials: S
authors.lastname: Sankarapandi
authors.forename: M
authors.initials: M
authors.lastname: Sukumar
authors.forename: P
authors.initials: P
authors.lastname: Balaram
authors.forename: P T
authors.initials: PT
authors.lastname: Manoharan
mesh_terms: D000595:Amino Acid Sequence; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D012997:Solvents; D013113:Spin Labels; D013438:Sulfhydryl Compounds / Q000737:chemistry; D013696:Temperature
chemical_list: D005609:Free Radicals; D010455:Peptides; D012997:Solvents; D013113:Spin Labels; D013438:Sulfhydryl Compounds