AMHERST, Mass.(1/6/96)-
Scientists have long envied the strength and elasticity of
spider's silk, but have been unable to synthesize it. Now
researchers at the University of Massachusetts report progress
in creating spider's silk using genetic engineering techniques.
Dragline silk is the fiber from which spiders make the
scaffolding of their webs. It has been estimated by scientists
to be at least five times as strong as steel, twice as elastic
as nylon, waterproof and stretchable.
"Dragline spider silk is actually stronger than Kevlar synthetic
fiber- and Kevlar is several times stronger than steel," says
polymer scientist David Tirrell who wrote a review for the
journal Science describing the current research of several
groups around the country trying to replicate the properties of
spider silk. Tirrell is well-known for his research in
"bioengineered materials," a new area of polymer research
involving the creation of synthetic proteins to make materials
with advanced properties.
"The properties of spider silk have impressed naturalists for
thousands of years," says Tirrell, "but until recently we
couldn't begin to think of making it in the lab. The advent of
modern biotechnology has finally given us the tools to study the
molecular design of spider silk fiber, -- and the means for
replicating natural spider silk in the lab using established
recombinant DNA techniques."
Tirrell reports that the primary constituents of spider silk
turn out to be the two simplest amino acids, glycine and
alanine, and he notes that researchers at Cornell have recently
discovered that the alignment of these amino acids is
responsible for spider silk's incredible strength.
"Understanding the alignment of the amino acids in the spider
silk will give us insights into ways of duplicating the spider's
work," says Tirrell. "We can use techniques commonly employed in
recombinant DNA research to synthesize the silk."
In designing a bioengineered polymer, Tirrell manipulates the
machinery of protein synthesis to his advantage by creating
genes that will produce the amino acid sequence yielding the
desired product -- in this case dragline silk.
Tirrell and other material scientists are currently using such
techniques to create a whole new class of bioengineered
materials. Basically, they clone a specific gene and insert it
into bacteria such as Escherichia coli. The bacteria then
manufacture the desired protein.
Spider silk, for instance, could be made in the lab by taking an
arachnid's genes and inserting them into bacteria to produce
that insect's strong, durable thread. The bacteria reproduce
and eventually form a cloned colony that produces the synthetic
polymer by way of protein synthesis.
Such synthetic proteins could be tailored to eventually degrade
in the human body or they could be made much more resistant to
degradation. Such degradation has been the subject of much of
Tirrell's work.
"The study of dragline silk offers insights into the behavior of
biological materials that will return practical dividends," says
Tirrell. "Uncovering the spider's secrets could lead us in
exciting new directions for materials research."
"Putting a New Spin on Spider Silk" appeared in the
January 5, 1996 issue of Science magazine.
Related information on the Internet
Arachnology Home Page
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