Fascinating Spider Silk

Apr 04, 2007

Stronger than steel and more elastic than rubber: spider silk is unsurpassed in its expandability, resistance to tearing, and toughness. Spider silk would be an ideal material for a large variety of medical and technical applications, and researchers are thus interested in learning the spiders’ secrets and imitating their technique.

A team lead by Thomas Scheibel at the Technical University of Munich has now made a step in the right direction. As they report in the journal Angewandte Chemie, the interaction between hydrophilic (water friendly) and lipophilic (fat friendly) properties of the silk proteins plays an important role in the spinning process.

Fundamentally, the spinning of spider silk represents a phase change from a solution into a solid thread; but the exact details of this process are largely unknown. The silk used by orb weaver spiders to spin the edges and spokes of their webs and to rappel away in the face of danger is made of two different proteins.

The Munich team has now successfully used genetic engineering to produce one of the spider silk proteins of the European garden spider (Araneus daidematus). While purifying the protein by dialysis, the researchers observed the separation of two different fluid phases. Whereas one phase consisted of protein dimers, the second consisted of oligomers—multiple protein units linked together. After the addition of potassium phosphate, a natural initiator of silk aggregation, the liquid could be pulled into threads. “It is clearly not a structural change in the protein, but rather the degree of oligomerization that is crucial for thread formation,” concludes Scheibel.

The silk solution in the spider’s silk gland has a very high protein concentration. This solution also contains a high concentration of sodium chloride, which suppresses oligomer formation. If the sodium chloride is removed, the proteins aggregate into oligomers.

In addition, the pH value also plays a crucial role in web production: within the silk gland, the pH is relatively high, but within the spinning duct it drops to a slightly acidic level. No phase separation was observed for the synthetic spider protein when the pH was maintained at an alkaline level. At high pH, the normally uncharged tyrosine groups in the protein are deprotonated, which gives them a negative charge. This charge weakens the interactions between the hydrophobic, lipophilic regions of the proteins, which are necessary for oligomerization.

“Our insights form a foundation for the establishment of an effective spinning process for the production genetically engineered spider silk,” hopes Scheibel.

Citation: Thomas Scheibel, The Amphiphilic Properties of Spider Silks Are Important for Spinning, Angewandte Chemie International Edition 2007, 46, No. 19, doi: 10.1002/anie.200604718

Source: Angewandte Chemie

Explore further: Intracellular imaging gets interactive

add to favorites email to friend print save as pdf

Related Stories

China Telecom profit rises as mobile data grows

27 minutes ago

China Telecom Ltd., one of the country's three main state-owned carriers, said Wednesday its profit rose 11.8 percent in the first half of the year as its Internet and mobile data businesses grew.

Biotech firm's GM mosquitoes to fight dengue in Brazil

1 hour ago

It's a dry winter day in southeast Brazil, but a steamy tropical summer reigns inside the labs at Oxitec, where workers are making an unusual product: genetically modified mosquitoes to fight dengue fever.

Snapchat valued at $10 bln

1 hour ago

US media on Tuesday reported that Snapchat was valued at $10 billion based on funding pumped into the startup by a powerhouse Silicon Valley venture capital firm.

Japan lab unable to replicate 'stem cell' findings

1 hour ago

Researchers in Japan have been unable to replicate experiments that were hailed earlier this year as a "game-changer" in the quest to grow transplant tissue, amid claims evidence was faked, a report said ...

Recommended for you

Team pioneers strategy for creating new materials

10 hours ago

Making something new is never easy. Scientists constantly theorize about new materials, but when the material is manufactured it doesn't always work as expected. To create a new strategy for designing materials, ...

Plug n' Play protein crystals

15 hours ago

Almost a hundred years ago in 1929 Linus Pauling presented the famous Pauling's Rules to describe the principles governing the structure of complex ionic crystals. These rules essentially describe how the ...

Protein glue shows potential for use with biomaterials

Aug 28, 2014

Researchers at the University of Milan in Italy have shown that a synthetic protein called AGMA1 has the potential to promote the adhesion of brain cells in a laboratory setting. This could prove helpful ...

User comments : 0