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Date of Award

2011

Document Type

Thesis - Pacific Access Restricted

Degree Name

Master of Science (M.S.)

Department

Biological Sciences

First Advisor

Craig A. Vierra

First Committee Member

Geoff Lin-Cereghino

Second Committee Member

Douglas C. Weiser

Abstract

Spider silk is renowned for its extraordinary mechanical properties, having a balance of high tensile strength and extensibility. To date, the majority of studies have focused on the production of dragline silks from synthetic spider silk gene products. Here we report the first mechanical analysis of synthetic egg case silk fibers spun from the Latrodectus hesperus tubuliform silk proteins, TuSp1 and ECP-2. We provide evidence that recombinant ECP-2 proteins can be spun into fibers that display mechanical properties similar to other synthetic spider silks. We also demonstrate that silks spun from recombinant thioredoxin-TuSp 1 fusion proteins that contain the conserved C-terminal domain exhibit increased extensibility and toughness when compared to the identical fibers spun from fusion proteins lacking the C-terminus. Mechanical analyses reveal that the properties of synthetic tubuliform silks can be modulated by altering the post-spin draw ratios of the fibers . Fibers subject to increased draw ratios showed elevated tensile strength and decreased extensibility, but maintained constant toughness.

Wide-angle X-ray diffraction studies indicate that post-drawn fibers containing the Cterminal domain of TuSp 1 have more amorphous content when compared to fibers lacking the C-terminus. Taken together, these studies demonstrate that recombinant tubuliform spidroins that contain the conserved C-terminal domain with embedded protein tags can be effectively spun into fibers, resulting in similar tensile strength but increased extensibility relative to non-tagged recombinant dragline silk proteins spun from equivalently sized proteins.

Pages

41

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