Solid‐state NMR relaxation studies of Australian spider silks

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Abstract
Solid‐state NMR techniques were used to study two different types of spider silk from two Australian orb‐web spider species, Nephila edulis and Argiope keyserlingi. A comparison of 13C‐T1 and 1H‐T1ρ solid‐state NMR relaxation data of the Ala Cα, Ala Cβ, Gly Cα, and carbonyl resonances revealed subtle differences between dragline and cocoon silk. 13C‐T1ρ and 1H‐T1 relaxation experiments showed significant differences between silks of the two species with possible structural variations. Comparison of our data to previous 13C‐T1 relaxation studies of silk from Nephila clavipes (A. Simmons et al., Macromolecules, 1994, Vol. 27, pp. 5235–5237) also supports the finding that differences in molecular mobility of dragline silk exist between species. Interspecies differences in silk structure may be due to different functional properties. Relaxation studies performed on wet (supercontracted) and dry silks showed that the degree of hydration affects relaxation properties, and hence changes in molecular mobility are correlated with functional properties of silk. © 2002 Wiley Periodicals, Inc. Biopolymers 61: 287–297, 2002