Ultimately, this cross-linking is what gives the spider silk threads their enormous tensile strength. The small crystallites first formed in the parallel cross-linking of the protein chains following the controlled unfolding of the C terminal domain are connected to each other via the N terminal domains of the spider silk protein to form a very long chain. "This is the effect that eventually explains the enormous tensile strength of the spider silk thread," says Kessler. To date, this ingenious form of cross-linking called "multivalence" has not been implemented in artificial polymers. "Most polymer chemists focus on the length of the thread. So far, no one has come up with the approach of cross-linking the ends of the threads and thereby opening the door to virtually unlimited lengths of polymer chains," beleives Kessler. These new findings may provide chemists with a model for manufacturing new materials with improved characteristics.
The scientists used the method of nuclear magnetic resonance (NMR) to analyze the structure of spider silk. Segments of spider silk are dissolved under conditions similar to those found in spider organs and exposed to radio wave impulses in a very strong magnetic field. The scientists can deduce the exact molecular structure from the "response" of the molecules. Using this method, environmental influences (e.g. salt concentration and pH value) can be studied accurately under simulated natural conditions. The development and application of NMR methods to biomolecules has been a longstanding focus of the Bavarian NMR Center in Garching.
|Contact: Dr. Markus Bernards|
Technische Universitaet Muenchen