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A worm with jaws that contain unusually large amounts of copper relies on a single protein to build its fangs

Left: a bloodworm’s fangs; right: Scanning electron microscope image of a single fang Matter/Wonderly et. al.

Left: a bloodworm’s fangs; right: Scanning electron microscope image of a single fang

Small sea creatures called bloodworms can burrow down several metres into the mud of the ocean floor. They have venom-injecting jaws that contain an unusually high level of copper – and now we know that a simple protein is responsible for these impressive fangs, which could inspire new ways of building materials.

Herbert Waite at the University of California, Santa Barbara, and his colleagues have been studying the 2-millimetre-long jaws of this bloodworm (Glycera dibranchiata), which are made up of 10 per cent copper and last for the worm’s entire five-year lifespan.

“You’ve got a little worm that’s making a jaw that’s as hard and stiff as bronze, and some ceramics as well – and they’re doing this autonomically,” he says.

To understand how, the team used advanced molecular and mechanical analysis techniques and modelling to investigate the composition and detailed functions of the worms’ jaws.

The group discovered that it is governed by a protein that controls a multistep process, which starts by binding copper from the environment, then mixing this copper in an aqueous solution, then separating it to produce a dense liquid that catalyses the conversion of an available amino acid into melanin.

Read more: Material inspired by blood vessels can extract uranium from seawater

While melanin often serves as a pigment for colour traits in other animals, it seems to make the bloodworm’s jaws more resistant to wear, says Waite.

“Together, these form a composite like that in rubber-filled reinforced tires, or fibreglass, and they involve so much less machinery than the industry [does],” he says.

The protein’s relatively simple structure is surprising because, in biochemistry, catalysts are usually based on much more complex proteins, and the protein does more than just catalyse. “It really does boggle the mind how a low-complexity system like that can do that many different basically unrelated tasks to come up with a composite material,” says Waite.

The findings could trigger engineers to improve the design and manufacturing of composite materials, like concrete and rubber-filled tires, which could – in a sense – help build themselves, he says.

Journal reference: Matter, DOI: 10.1016/j.matt.2022.04.001

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