CHAMPAIGN, Ill. Researchers have developed a simple method of making short protein chains with spiral structures that can also dissolve in water, two desirable traits not often found together. Such structures could have applications as building blocks for self-assembling nanostructures and as agents for drug and gene delivery.
Led by Jianjun Cheng, a professor of materials science and engineering at the University of Illinois, the research team will publish its findings in the Feb. 22 edition of the journal Nature Communications.
Materials scientists have been interested in designing large polymer molecules that could be used as building blocks for self-assembling structures. The challenge has been that the molecules generally adopt a globular, spherical shape, limiting their ability to form orderly aggregates. However, polypeptides chains of amino acids such as proteins can form helical structures. Short polypeptide chains that adopt a spiral shape act like cylindrical rods.
"If you have two rigid rods, one positive and one negative, right next to each other, they're going to stick to each other. If you have a way to put the charge on the surface then they can pack together in a close, compact way, so they form a three-dimensional structure," Cheng said.
However, it is difficult to make helical polypeptides that are water-soluble so they can be used in solution. Polypeptides gain their solubility from side chains molecular structures that stem from each amino acid link in the polypeptide chain. Amino acids with positive or negative charges in their side chains are needed to make a polypeptide disperse in water.
The problem arises when chains with charged side chains form helical structures. The charges cause a strong repulsion between the side chains, which destabilizes the helical conformation. This causes water-soluble polypeptides to form random coil structures instead of the desired helices.<
|Contact: Liz Ahlberg|
University of Illinois at Urbana-Champaign