Synthesis and conformational study of silk model polypeptides [Ala-Gly] 12 by solid-state NMR
A series of well-defined model polypeptides of Bombyx mori silk fibroin, [Ala-Gly] n ( n=12 and 5–9), [Ala d4Gly] 12 and [Gly d2Ala] 12, (where Ala, Gly, Ala d4 and Gly d2 denote l-alanine, glycine, 2,3,3,3-deuterated l-alanine and 2,2-deuterated glycine residues, respectively), were successfully sy...
Saved in:
Published in | Journal of molecular structure Vol. 649; no. 1; pp. 155 - 167 |
---|---|
Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
Elsevier B.V
01.04.2003
|
Subjects | |
Online Access | Get full text |
Cover
Loading…
Summary: | A series of well-defined model polypeptides of
Bombyx mori silk fibroin, [Ala-Gly]
n (
n=12 and 5–9), [Ala
d4Gly]
12 and [Gly
d2Ala]
12, (where Ala, Gly, Ala
d4 and Gly
d2 denote
l-alanine, glycine, 2,3,3,3-deuterated
l-alanine and 2,2-deuterated glycine residues, respectively), were successfully synthesized by an automatic solid phase peptide synthesizer. Followed by treatment with 9
M lithium bromide (LiBr) solution to convert their conformation from the silk II to the silk I form. We determined the intrinsic
1H,
13C and
15N NMR chemical shifts of Ala and Gly residues, characteristic to the silk I and silk II forms in
Bombyx mori, by high-resolution and solid-state
13C CP-MAS,
1H CRAMPS,
1H–
13C HETCOR and
15N CP-MAS NMR measurements. Next, we demonstrated that it is necessary at least 12 amino acid residues (
n=6) in the [Ala-Gly]
n-I series for the formation of stable silk I form by
13C CP-MAS NMR. Finally, we found that the intrinsic
1H and
13C chemical shifts of the specific deuterium labeled polypeptides, [Ala
d4-Gly]
12 and [Gly
d2-Ala]
12, cause a meaningful chemical shift displacement, suggesting that the deuterium interacts with proton and/or carbon atoms in the solid state. Thus, the selective deuterium labeling has a potential to useful for the structural analysis by
1H NMR in the solid state. |
---|---|
ISSN: | 0022-2860 1872-8014 |
DOI: | 10.1016/S0022-2860(03)00054-1 |