Harrington agreed. “I don’t think these are mutually exclusive,” he said. “You might have different sorts of phase transitions that are occurring at different stages of the processing.”
Still, there’s more to understand about how these interactions add up on this factory line. There are likely other significant amino acid interactions that the researchers haven’t yet been able to map out in detail. They also want to look for triggers that initiate the process beyond phosphate. “There could be a range of other things that are driving structural changes in these proteins,” Chris Holland said. “We don’t know all of the switches yet.”
Superior Materials
Describing the entirety of the intricate silk-spinning process will take a lot of effort, but the payoff could be huge. Spiders produce small amounts of usable silk compared to silkworms, which have been reared for their cocoons for more than 4,000 years. It takes thousands of silkworms to make a silk shirt; it would take around 1 million spiders, in part because they don’t produce cocoons that can be easily processed. There is a more practical reason: Their cannibalistic nature makes them difficult to keep because each spider needs its own container.
Producing spider silk in the lab could result in a new range of strong yet flexible materials. Kevlar, a synthetic fiber, is currently our toughest material, but it requires processing at very high temperatures and acidic conditions. “Here, you have an organism like a spider or a mussel,” Harrington said, “which is basically making a superior material under ambient conditions in seawater or in just plain air.”
Humans haven’t figured out how to match those organisms yet. When scientists synthesize spider silk in the lab, using the exact sequence of amino acids to build a spidroin protein, the resulting silk is not as strong as natural silk. “Something is happening there that we’re also struggling to mimic,” Chalek said. He thinks additional strength must be provided by something beyond the protein’s beta sheets, arising from other aspects of silk’s structure, or perhaps from parts of the spidroin protein frequently left out of synthetic silk solutions.
“I think once we really understand those blueprints,” Chris Holland said, “we’ll be able to do more stuff with silk.”