Orientational order of Australian spider silks as determined by solid‐state NMR

A simple solid‐state NMR method was used to study the structure of 13 C‐ and 15 N‐enriched silk from two Australian orb‐web spider species, Nephila edulis and Argiope keyserlingi. Carbon‐13 and 15 N spectra from alanine‐ or glycine‐labeled oriented dragline silks were acquired with the fiber axis aligned parallel or perpendicular to the magnetic field. The fraction of oriented component was determined from each amino acid, alanine and glycine, using each nucleus independently, and attributed to the ordered crystalline domains in the silk. The relative fraction of ordered alanine was found to be higher than the fraction of ordered glycine, akin to the observation of alanine‐rich domains in silk‐worm ( Bombyx mori ) silk. A higher degree of crystallinity was observed in the dragline silk of N. edulis compared with A. keyserlingi , which correlates with the superior mechanical properties of the former © 2006 Wiley Periodicals, Inc. Biopolymers 82:134–143, 2006 This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com