Long-distance rotational echo double resonance measurements for the determination of secondary structure and conformational heterogeneity in peptides
✍ Scribed by Boris Arshava; Michael Breslav; Octavian Antohi; Ruth E. Stark; Joel R. Garbow; Jeffrey M. Becker; Fred Naider
- Book ID
- 104358020
- Publisher
- Elsevier Science
- Year
- 1999
- Tongue
- English
- Weight
- 589 KB
- Volume
- 14
- Category
- Article
- ISSN
- 0926-2040
No coin nor oath required. For personal study only.
✦ Synopsis
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 ˚13 15
Ž
. was the evaluation of long-distance ) 5 A interactions using C-N dephasing. Detailed studies of specifically labeled melanostatin and synthetic analogs of the a-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 a-factor mating pheromone from Saccharomyces cereÕisiae Ž . 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 a-factor assumes a distorted type-I b-turn in the w Ž .
x