Local conformation of serine residues in a silk model peptide, (Ala–Gly–Ser–Gly–Ala–Gly)5, studied with solid-state NMR:REDOR

Structural Analysis of the Synthetic Peptide (Ala-Gly-Ser-Gly-Ala-Gly)5, a Model for the Crystalline Domain of Bombyx mori Silk Fibroin, Studied with 13C CP/MAS NMR, REDOR, and Statistical Mechanical Calculations

“…REDOR was used for the purpose. The experimental Δ S /S 0 values were plotted against dipolar evolution time for (AGSGAG) 2 Ala[1- 13 C]GlySer[ 15 N]Gly-AlaGly(AGSGAG) 2 (see Figure for an example) and some of the plots have already been reported previously . As a starting point, the theoretical REDOR curve was calculated by assuming the distance, between [1- 13 C]Gly and [ 15 N]Gly nuclei in the sequence, [1- 13 C]Gly-Ser-[ 15 N]Gly of 4.75 Å as in the antiparallel β-sheet structure obtained from crystal structure of B.…”

“…The experimental ΔS/S 0 values were plotted against dipolar evolution time for (AGSGAG) 2 Ala[1-13 C]GlySer-[ 15 N]Gly-AlaGly(AGSGAG) 2 (see Figure 3 for an example) and some of the plots have already been reported previously. 26 As a starting point, the theoretical REDOR curve was calculated by assuming the distance, between [1-13 C]Gly and [ 15 4 shows these data (black) plotted against the residue position within (AGSGAG) 5 and corresponding plot (gray) for (AG) 15 reported previously. 11,12 Comparison of the plots for (AG) 15 and (AGSGAG) 5 show that on the whole, the fractions of the distorted β-turn and/or random coil component were higher in (AGSGAG) 5 except for the two Ala residues at the N-terminal sites.…”

A review on the structure of Bombyx mori silk fibroin fiber studied using solid-state NMR: An antipolar lamella with an 8-residue repeat

“…Experiments carried out on peptides doubly labeled with [ 13 C] and [ 15 N] at different locations are very useful for studying peptide and protein structures containing turns, because the measured atomic distance between C and N nuclei is shorter if these nuclei are in a turn. 37,62,[81][82][83] Table 1 compares the observed interatomic distances between the labeling sites determined Table 1 from REDOR plots, with the predicted averaged interatomic distances calculated from the percentage composition of -turn and -sheet at that location as determined by deconvolution of the Ala C CP/MAS spectra (Figure 7(II)). If (AG)15 adopts a pure sheet structure, all the interatomic observed distances should be longer than the distances determined by REDOR by 0.2-0.3 Å for the peptides D1-D4, and 0.8 Å for D5.…”