Lab-made proteins stretch like life.

Lab-made proteins stretch like life

By the time a person reaches the age of 60, some of the elastic fibers in the aortic arch of his or her heart have survived about 2 billion stretch-relaxation cycles, notes molecular biophysicist Dan W. Urry of the University of Alabama at Birmingham. The fibers are made of an unusually long-lived and stretchy structural protein known as elastin.

Urry has been making his own versions of bioelastic protein since the early 1970s, when he received a call from a colleague who had just uncovered elastin's molecular structure -- a repetitive arrangement consisting largely of units of the amino acid string valine-proline-glycine-valine-glycine. Some of his synthetic bioelastics are undergoing animal testing for potential use in preventing scarring after abdominal surgery. Urry and his colleagues start by chemically linking many of these or similar units, which subsequently fold into Slinkystyle coils. They then use gamma rays to cross-link the molecules into strips, sheets and other shapes. By slightly altering the composition of the component peptides, the researchers can engineer bioelastics that stretch and contract in response to different environmental cues. "You can drive the elastomers between folded [contracted] and unfolded [streteched] states using thermal, mechanical, or chemical influences," Urry says.

Most recently, the team has figured out how to fashion the material into a transparent form that is about as refractive as ocular lens tissue. Urry, who recently formed a company called Bioelastics, Inc., with several University of Alabama colleagues, says he hopes eventually to develop the material as a lens replacement. Closer to the surgeon's shelf, however, are the bioelastic sheets for preventing the scar tissue formation that often occurs after abdominal surgery. Such scarring, called adhesions, can lead to postsurgical complications such as blocked intestines.