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A fishy approach: Ben develops biomimetic antifreezes to stop ice in its tracks

Freezer burn is about to meet its fatal thaw.

Using the techniques of modern synthetic organic chemistry, Robert Ben’s research team has developed an artificial antifreeze that could eliminate freezer burn in frozen foods within five to 10 years. The work takes its lead from fish that thrive in polar waters by all rights cold enough to freeze them solid mid swish.

Ben’s biomimetic antifreeze—or derivatives resulting from future research—also promise to help protect fruit crops from killer frosts, roads and planes from dangerous icing, and transplantable human tissues and organs from the ravages of low temperature storage. And that’s just for starters.

Ben’s antifreeze, which mimics the effects of a substance produced by Arctic and Antarctic deep sea teleost fish, is safe enough for use in living organisms and boasts several improvements on its natural counterpart. It is thousands of times more biologically and chemically stable than the biological version and is much easier and cheaper to produce.

Worldwide interest in Ben’s work is far from lukewarm. Featured in the September/October issue of Bioconjugate Chemisty, the peer-reviewed journal the American Chemical Society, news of his discovery has been picked up by most major wire services and appeared in several of the hottest on-line science newsletters, including New Scientist.

An assistant professor of chemistry who joined the faculty at Binghamton in 1998, Ben recently received a five-year National Institutes of Health grant of just under $1 million to continue his antifreeze work, which also enjoys ongoing support from the American Chemical Society, the world’s largest scientific society, and a small Boston-based biotech company, A/F Protein, Inc.

Many organisms, including plants, grasses, trees, insects, amphibians and fish produce small amounts of antifreeze proteins, or AFPs, that help them survive or even thrive in the cold. But certain deep-sea fish from the teleost group, such as Atlantic cod and winter flounder, produce another substance—the substance Ben works with—called antifreeze glycoproteins, or AFGPs.

Ben’s work focuses on AFGPs because they are more attractive than AFPs for chemical synthesis. That’s because they are structurally less diverse, offering chemists a more standard model from which to work.  They also demonstrate a unique ability to protect living tissues not only from the ravages of freezing, but also as they are cooled to just less than freezing temperatures, a feature that greatly enhances potential applications.

Scientists have known about AFGPs for just over 30 years, but there is still much to learn about how the antifreezes actually prevent the growth of ice at the molecular level, Ben said. What is known is that the mitigating effects are not the result of heat, do not depend on physical encapsulation of the ice crystals and do not involve thawing of existing ice crystals, he said.

Indeed ice crystals are routinely found floating within the cells of fish from polar waters, Ben said. The freezing points of both the fish and the polar waters they swim in is lower than zero because of their salt content. But these saltwater fish, which have a freezing point of -0.7 Celsius, are only able to live in waters that reach temperatures of –1.8 Celsius because they produce AFGPs. Without the AFGPs, the fish would be frozen solid in a matter of seconds.

Though only tiny amounts of the biological antifreeze are needed to bind ice crystals and inhibit ice growth in fish, the use of naturally occurring AFGPs to combat ice in a host of commercial or medical applications is impractical. To collect, purify, isolate and extract naturally occurring biological antifreezes is labor intensive and costly— in terms of fish populations as well as dollars. Up to a ton of fish might have to be ground up and liquefied to obtain just a few grams of natural AFGP, Ben said.

As its name suggests, AFGP is a protein with sugars attached. Though biological AFGP molecules are structurally more homologous than AFP molecules, they are not easily produced using standard molecular biology techniques. That not only means that scientists haven’t studied them as well as AFPs,  it also means that Ben’s research team, which he says is the only organic chemistry laboratory in the world working on this problem, has a distinct advantage.

“You can trick a cell into making a protein for you, but it’s very difficult to get that protein glycosylated using standard molecular biology techniques,” Ben said. “Our advantage is that we can use the protocols and techniques of modern synthetic organic chemistry to build AFGPs and to build analogues that can help us to better understand how they function.”

Ben is quick to share credit for the new antifreeze with his graduate students.

“While I provide the fundamental ideas, I have some really dedicated graduate students who make this very difficult chemistry really work,” he said. He expects his lab to continue conducting structure-function research with AFGP analogues over the next few years in order to better understand how antifreeze glycoproteins work to bind ice crystals and arrest their rapid growth, he said.

“It’s difficult to design something better if you don’t know what you’re designing from,” he said.

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