The training included a controlled feeding study to measure the long-term effects of a high-salt diet. The stable spider silk fiber is formed.Crew members during a simulated mission to Mars at the Russian Academy of Sciences’ Institute of Biomedical Problems (IBMP) in Moscow. The long protein chains are aligned in parallel, thus placing the areas responsible for interlinking side by side. Furthermore, the flow in the narrow spinning duct results in strong shear forces. This renders two salt bridges of the control domain unstable, and the chain can unfold. ‘When the protected proteins enter the spinning duct, they encounter an environment with an entirely different salt concentration and composition. ‘Interlinking is thus effectively prevented.” The protein chains are stored with the polar areas on the outside and the hydrophobic parts of the chain on the inside, ensuring good solubility in the aqueous environment. “‘Under storage conditions in the silk gland these control domains are connected pair-wise in such a way that the interlinking areas of both chains can not lie parallel to each other,’ Thomas Scheibel explains. The ability to make a strong fiber that can be readily molded into specific shapes might be applied to making scaffolds for artificial organs.įinally, the overall process of fiber-making might be programmed into robots, enabling them to use environmental conditions to guide the production of variable fibers with minimal input from humans. Most directly, the process could be applied to make thread that can be woven into fabrics for clothing, household goods, and more without the need for high temperatures, harsh chemicals, or other environmentally unfriendly inputs or byproducts.īecause so many details of the pultrusion process-speed, chemical environment, and more-affect the characteristics of the final product, spider silk production can be also applied to making fibers that conform to very particular specifications necessary for technical uses, such as water filtration. Potential applications of a spider’s ability to turn a liquid into a durable fiber are all but endless. The resulting structure is then both very strong and very stretchy, giving the finished silk its famous properties, perfect for capturing dinner. Some sections of the silk connect many times over with bonds forming between them like rungs between two sides of a ladder (a structure called a “beta sheet”). This is an essential part of the spinning process, as it allows the viscous, protein-filled solution to flow more easily through the spinning duct, reducing the energy requirements for spinning.

The narrow duct also creates shear forces that physically force the unfolded protein molecules into elongated shapes that can more easily line up in parallel to one another. This allows the protein to start unfolding into a more linear configuration that can more easily move through the spinning duct. This reduction in pH causes the salt bridges to come apart. It does this by catalyzing the conversion of carbon dioxide and water into carbonic acid, and vice versa. As the protein moves through the duct, the enzyme carbonic anhydrase helps to create a pH gradient that is slowly lowered from about 8 to about 5.7 (becoming more acidic). Large, folded proteins can’t fit through, so they must be unfolded. When the liquid silk is pulled from inside the spider, it goes through the spinning duct, which is a narrow tunnel.

At lower pH levels, the salt bridge becomes unstable, and the protein structure can start to unfold. Salt bridges help to stabilize the proteins and keep them folded. While silk proteins vary between spider species, they all appear to share a particularly important region called a “salt bridge.” Salt bridges are pairs of protein regions that are oppositely charged and therefore attracted to one another. How do spiders do it? It all has to do with the design of the silk’s protein molecules, the solutions they’re stored in, and the way they’re molded as they pass through a spider’s silk ducts. Second, the fiber itself takes on a variety of traits, with variations in thickness, stickiness, stretchiness, and other characteristics depending on how the fiber is “pultruded,” or pulled from a spider’s body as the spider moves away from an end that’s stuck to a surface. For one thing, spiders store the proteins that make up the fiber in liquid form inside their bodies, preventing them from hardening into a fiber there. Microscopy and chemistry have enabled humans to look closer though, and see it for the natural wonder that it is. At first glance, spinning spider silk thread may not seem a remarkable feat.

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