Premium
Structure of Bombyx mori silk fibroin before spinning in solid state studied with wide angle x‐ray scattering and 13 C cross‐polarization/magic angle spinning NMR
Author(s) -
Asakura Tetsuo,
Yamane Tsutomu,
Nakazawa Yasumoto,
Kameda Tsunenori,
Ando Kazuto
Publication year - 2001
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/1097-0282(20010415)58:5<521::aid-bip1027>3.0.co;2-t
Subject(s) - fibroin , silk , magic angle spinning , bombyx mori , random coil , chemistry , solid state nuclear magnetic resonance , spinning , crystallography , alanine , polymer chemistry , nuclear magnetic resonance spectroscopy , nuclear magnetic resonance , materials science , stereochemistry , composite material , amino acid , physics , circular dichroism , biochemistry , gene
The structure of a crystalline form of Bombyx mori silk fibroin, commonly found before the spinning process (known as silk I), has been proposed as a repeated β‐turn type II ‐like structure by combining data obtained from solid‐state two dimensional spin‐diffusion nuclear magnetic resonance and rotational‐echo double‐resonance (T. Asakura et al., J Mol Biol, in press). In this paper, the WAXS pattern of alanine‐glycine alternating copolypeptide, (Ala‐Gly) 15 with silk I form which was used for a silk I model of B. mori silk fibroin was observed. The pattern calculated with the silk I model proposed by us is well reproduced the observed one, indicating the validity of the proposed silk I model. In addition, two peptides of the other repeated sequences which contain Tyr or Val residues in the silk fibroin,23 were synthesized; (Ala‐Gly‐Tyr‐Gly‐Ala‐Gly) 5 and (X‐Gly) 15 where X is Tyr for the 7th, 15th and 23th residues, and Val for the 11th residue and Ala for other residues. There are no sharp peaks in the WAXS patterns, and therefore both samples are in the non‐crystalline state. This is in agreement with the 13 C CP/MAS NMR result, where the conformation is mainly random coil. © 2001 John Wiley & Sons, Inc. Biopolymers 58: 521–525, 2001