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UConn Chemist Discovers New Way to Stabilize Proteins

 

Challa Kumar, professor of chemistry, center, with graduate students Caterina Riccardi, left, and Inoka Deshapriya in the lab. (Photo by Peter Morenus)

Challa Kumar, professor of chemistry, center, with graduate students Caterina Riccardi, left, and Inoka Deshapriya in the lab. (Photo by Peter Morenus)

A UConn research team has found a way to stabilize hemoglobin, the oxygen carrier protein in the blood, a discovery that could lead to the development of stable vaccines and affordable artificial blood substitutes.

The team’s novel approach involves wrapping the polymer poly(acrylic acid) around hemoglobin, protecting it from the intense heat used in sterilization and allowing it to maintain its biological function and structural integrity.

In addition to having potential applications in the stabilization of vaccines and development of inexpensive artificial blood, the stabilizing polymer also allows vaccines and other biomedical products to be stored for longer periods without refrigeration. It could also have applications in biomaterials, biosensors, and biofuels.

“Protein stability is a major issue in biotechnology,” says Challa V. Kumar, UConn professor of chemistry and biochemistry and the primary investigator on the project. “What we’ve done is taken this protein molecule and wrapped it up in a polymer chain in order to stabilize it. In thermodynamics terms, we have restricted the entropy of the denatured state of the protein and stabilized it beyond our expectations. The system also exhibits a high degree of reversibility. The protein can be denatured and renatured many, many times. This is the very first example of its kind in the literature of all protein science. No one has ever been able to achieve this kind of stability for proteins.”

A popular example of denaturation can be found in the protein present in eggs. As the egg is cooked and the protein around the yolk turns white, the protein in the egg is denatured and cannot return to its prior, natural state. Likewise, when proteins in a living cell are exposed to heat they become denatured, which disrupts their activity and can lead to cell death. When protein is a critical element in a vaccine and breaks down, the product becomes useless.

In searching for a viable material to serve as a protein stabilizer, Kumar’s team found one that is readily available, inexpensive, and can be modified chemically for further improvements.

The poly(acrylic acid) used in the study is the same material found in disposable diapers, and one of the most abundant synthetic polymers on the planet. This particular polymer, says Kumar, is very hydrophilic, meaning it likes water. The polymer naturally binds to hemoglobin, creating a tight seal that protects the protein molecule and allows it to retain its structural integrity even after heating it to 120˚C for extended periods of time (steam sterilization).

Read more at UConn Today

By Colin Poitras


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