In lab experiments, Yu and his colleagues have shown that this kind of molecular marriage does take place. They attached fluorescent tags to the peptides and observed the glow in collagen that had been mixed with the smaller molecules. Exactly how and why the collagen and the peptides join is uncertain. But researchers know that collagen molecules form a distinctive triple-helix in which three long protein strands intertwine like rope. Yu speculates that because the smaller collagen mimetic peptides have a propensity to make similar triple-helix structures, they are naturally attracted to collagen molecules. He believes the peptides make themselves at home within gaps formed by loose collagen strands.
This linkup opens the door to new medical treatments, Yu says, because it is easy to attach bioactive agents to the peptides. When the peptides bind with collagen, these attached agents can dramatically change the way collagen behaves in the body. For example, collagen normally attracts cells to close up a wound and form scar tissue. But this property is not always desirable; a clot can be dangerous inside a blood vessel or at certain injury sites, where scar tissue can interfere with the formation of new nerve connections.
Modified collagen can follow a different course. In their recent journal paper, Yu and his colleagues reported that they had attached a chemical, polyethylene glycol, to the peptides, causing collagen to repel cells instead of attracting them. When the researchers added human cells to a lab dish, the cells migrated toward an untreated collagen film but avoided the modified collagen sample. This form of collagen could stop the formation of blood clots and scar tissue, and scientists may be able to use it to control the shape and organization of cells and tissue that are grown in a lab, Yu says.
Source:Johns Hopkins University