title: A DECODER NMR study of backbone orientation in Nephila clavipes dragline silk under varying strain and draw rate.
abstract: Using DECODER (direction exchange with correlation for orientation distribution evaluation and reconstruction) NMR, we probe the orientations of carbonyl carbons in [1-(13)C]glycine-labeled dragline silk under conditions of varying strain and fiber draw rate. A model-specific reconstruction of the molecular orientation distribution incorporating beta sheets and polyglycine II helices indicates that the structures' alignment along the fiber can be described by a pair of Gaussian distributions with full width at half-maxima of 20 and 68 degrees and approximately 45 and approximately 55% relative contributions to the signal intensity. The alignment along the fiber was found to change appreciably when the drawing tension on the fiber was relaxed in a sample drawn at 4 cm/s while little change was observed in a sample drawn at 2 cm/s. The degree of alignment along the fiber was found to increase with fiber draw rate.
authors.affiliation: Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, British Columbia V6T 1Z1, Canada.
authors.forename: Philip T
authors.initials: PT
authors.lastname: Eles
authors.forename: Carl A
authors.initials: CA
authors.lastname: Michal
mesh_terms: D000818:Animals; D019906:Nuclear Magnetic Resonance, Biomolecular; D047011:Silk / Q000737:chemistry*; D013112:Spiders / Q000737:chemistry*
chemical_list: D047011:Silk