Rotational echo double resonance NMR spectroscopy is applied for the determination of the distance of intermolecular chains of pentapeptide, GAGAG (G: Gly, A: Ala), a model typical of the crystalline domain in Bombyx mori silk fibroin. 1:4 mixture of G[1-(13)C]AGAG and GAG[(15)N]AG with antiparallel beta-sheet structure was used to determine the distance of intermolecular hydrogen bonding between adjacent molecules within pleated sheet and the (13)C-(15)N interatomic distance was determined to be 4.3 A. On the other hand, 1:4 mixture of GAG[1-(13)C]AG and GAG[(15)N]AG gave information on the interpleated sheet arrangement. When we assumed the same distances between two interpleated sheets, the distance was calculated to be 5.3 A and the angle (15)N-(13)C-(15)N was 180 degrees.
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