What is a spider's silk made of?

★ wanayoo — archive 1999 http://howstuffworks.com/question87.htm

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Question

What is spider's silk made of? I have heard that it is incredibly strong.

Answer

Spider's silk is made up of chains of amino acids - in other words, it is simply a protein (see How Food Works for details on amino acids and proteins). The two primary amino acids are glycine and alanine. Spider silk is extremely strong - it is about 5 times stronger than steel and twice as strong as Kevlar of the same weight. Spider silk also has the ability to stretch about 30% longer than its original length without breaking, which makes it very resiliant.

Interesting Links:

Fiber engineers, meet thy master
Spider web information
Spider silk
Bacteria Developed to Produce Spider Silk
Bioengineered spider silk
Biomolecular self-assembling materials - very deep article, but figure 6 shows the structure of glycine and alanine amino acids in spider's silk.
Kevlar

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