title: Long-distance rotational echo double resonance measurements for the determination of secondary structure and conformational heterogeneity in peptides.
abstract: The utility of rotational echo double resonance (REDOR) NMR spectroscopy for determining the conformations of linear peptides has been examined critically using a series of crystalline and amorphous samples. The focus of the present work was the evaluation of long-distance (> 5 A) interactions using 13C-15N dephasing. Detailed studies of specifically labeled melanostatin and synthetic analogs of the alpha-factor yeast mating hormone show that nitrogen-dephased, carbon-observe REDOR measurements are reliable for distances up to 6.0 A, and that dipolar interactions can be detected for distances up to 7 A. By contrast, nitrogen-observe REDOR gives reliable results only for distances shorter than 5.0 A. To measure distances accurately, REDOR data must be corrected for the effects of natural-abundance spins. These corrections are particularly important for measuring long distances, which are of the greatest value for determining peptide secondary structure. We have developed a spherical shell model for calculating the effect of these background spins. The REDOR studies also indicate that in a lyophilized powder, the tridecapeptide alpha-factor mating pheromone from Saccharomyces cerevisiae (WHWLQLKPGQPMY) probably exists as a distribution of different turn structures around the KPGQ region. This finding revises previous solid-state NMR studies on this peptide, which concluded alpha-factor assumes a distorted type-I beta-turn in the Pro-Gly central region of the molecule [J.R. Garbow, M. Breslav, O. Antohi, F. Naider, Biochemistry, 33 (1994) 10094].
authors.affiliation: Department of Chemistry, College of Staten Island and the Graduate School of the City University of New York, 10314, USA.
authors.forename: B
authors.initials: B
authors.lastname: Arshava
authors.forename: M
authors.initials: M
authors.lastname: Breslav
authors.forename: O
authors.initials: O
authors.lastname: Antohi
authors.forename: R E
authors.initials: RE
authors.lastname: Stark
authors.forename: J R
authors.initials: JR
authors.lastname: Garbow
authors.forename: J M
authors.initials: JM
authors.lastname: Becker
authors.forename: F
authors.initials: F
authors.lastname: Naider
mesh_terms: D000465:Algorithms; D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D005612:Freeze Drying; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry*; D011487:Protein Conformation; D017433:Protein Structure, Secondary
chemical_list: D010455:Peptides