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Summary: 1990
INTRODUCTION
Most of the world's 40,000 species of spiders produce dragline silk
from major ampullate silk glands to spin lifelines and frames of
webs (Fig.1A,B). Dragline silk's impressive toughness
(work/volume ~5 greater than KevlarŪ
), high strength to weight
ratio (~5 greater than steel), immunological compatibility with
living tissue, and production under environmentally benign
conditions all make spider silk an important model for biomimetic
research (Gosline et al., 1986; Vadlamudi, 1995; Vollrath and
Knight, 2001; Vollrath and Porter, 2006). Many of these properties
result from the structure of silk proteins, which combine -sheet
crystals that interlock molecules together and stiffen fibers with less
organized `amorphous' regions of the proteins that allow molecular
mobility (Gosline et al., 1999; Hayashi et al., 1999; Termonia, 1994).
This composite structure results in fibers that are both strong and
stretchy and that resist crack propagation. Spiders depend upon these
properties for survival, yet the impressive performance of silk is
not limited solely to tensile mechanics. Here, we show that spider
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