Reveals the mechanism by which organisms use antifreeze proteins to maintain survival

If you think that antifreeze is just what you need to do to keep your car from freezing in winter, then think again. Plants and animals living in cold climates have natural antifreeze protein (AFP). Prevents the growth of ice crystals and the crystallization of organic fluid substances. Without this antifreeze protein, life forms will suffer freezing damage and even death.

The production of these antifreeze proteins is one of the main evolutionary approaches taken by various organisms including fish, insects, bacteria, plants and fungi. Researchers from Israel, Canada and the United States believe that understanding how this mechanism works is itself It is more important, and it also has an important impact on improving the world's food and pharmaceutical production.

Although half of the world ’s research has been carried out, the mechanism of producing natural antifreeze protein activity is still a mystery. One of the focuses of academic debate is about the chemical and physical characteristics involved in the interaction between antifreeze protein and ice crystals. In particular, The debate about whether the binding of antifreeze proteins to ice crystals is reversible and whether the persistence of these proteins in solution is necessary to prevent the growth of ice crystals has been ongoing.

The challenge to answer these questions stems from various technical problems associated with the growth of ice crystals and the tracking of tiny ice crystals under conditions that mimic the environment surrounding antifreeze proteins in nature.

In a new study, the researchers studied the antifreeze protein of yellow mealworm. This protein is highly active, and its ability to stop the growth of ice crystals is hundreds of times stronger than that of fish and plant antifreeze proteins. The relevant research results were published online in the PNAS journal on January 8, 2013, and the paper titled "Microfluidic experiments reveal that antifreeze proteins bound to ice crystals suffice to prevent their growth".

In this study, the researchers constructed a version of this antifreeze protein carrying a fluorescent label through biochemical means, allowing direct observation under a microscope. They injected this protein into a specially designed micro-channel containing a very small diameter channel Fluid equipment.

These microfluidic devices are placed in a cooling device designed for temperature control at a level of a few thousandths of a degree Celsius, so that ice crystals of 20 to 50 microns can be controlled to grow and melt, and all of them can be under the microscope. Make an observation.

Using this specially designed system, the researchers were able to confirm that the ice crystals grown and incubated in the antifreeze solution have been coated with the antifreeze protein and thus have been protected. They further confirmed that the antifreeze protein is directly and strong enough It binds to ice crystals to prevent the growth of ice crystals, even when there is no longer any further presence of this protein in solution.

These findings not only have scientific significance, but also have practical value. For example, fish antifreeze protein has been used in low-fat ice cream to prevent ice crystal recrystallization (ice recrystallization), which can maintain a soft creamy smooth Texture. Researchers say these proteins can also be used in other frozen foods to maintain the desired texture without adding more fat.

In medicine, antifreeze proteins can be used to improve the quality of sperm, eggs and embryos stored in the frozen state, as well as organs used for cryopreservation for transplantation. They can also be used in cryosurgery and agriculture.

Other antifreeze protein studies have focused on preparing recombinant plants and fish with improved survival rates under cold and dehydrated conditions. These recombinant crops may help improve the distribution of food worldwide.

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