Animals are cut from a cloth woven largely of collagen. This rope-like protein is the most abundant in the body, giving structure to tissues such as skin and cartilage, but to date chemists haven’t fully understood the source of collagen’s strength. A prevailing theory dictated that the molecule-a tightly wound triple helix-was braced by a scaffolding of water molecules. But research from the University of Wisconsin-Madison points to a different answer, one that not only helps explain collagen’s properties, but also might eventually expand the protein’s utility in cosmetic surgery, wound healing and perhaps even arthritis diagnosis and treatment.
Wisconsin biochemist Ronald Raines and his co-workers modified collagen so that it was incapable of forming the “water bridge” bonds previously thought to help hold the molecule together. The new form is able to endure temperatures more than 22 C higher than a model of natural collagen, probably because added fluorine atoms push the chains into a sturdy configuration, the researchers explain in the April issue of Nature.
Natural collagen is already a useful biomaterial, most famous for its starring role in the full lips and wrinkle-free faces of movie stars and models. But the protein tends to unravel in the body, so collagen injection must be repeated every few months. Raines believes that a more stable artificial collagen could be an advantage not only in plastic surgery but also in artificial tissues, organs and perhaps even in a protein “solder” that could be melted into wounds for sutureless healing.
MIT polymer engineer Ioannis Yannas says that the Wisconsin work is an important advance in understanding the structure of collagen. He cautions, however, that the findings don’t guarantee practical uses for artificial collagen. For one thing, the molecule must prove to be nontoxic. And there is a “big gap,” Yannas says, between knowing the chemical structure and developing a new biomaterial.
Brian Butcher-vice president for research at the Arthritis Foundation, which helped fund Raines’ research-says that the new insight into collagen “could have very important repercussions” for arthritis. The joint ailment is often the result of collagen-rich cartilage breaking down; Butcher sees the potential to develop better tools for detecting the destruction. In time, Butcher says, researchers might even learn how to replace or strengthen collagen structures in arthritic joints, reweaving the worn tissues with stronger stuff.
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