The same proteins that allow whales to dive without breathing for up to two hours could be harnessed by medical experts to develop useful synthetic blood, according to research published this week in the Journal of Biological Chemistry.
The quest to develop synthetic blood for use in human trauma patients has been two decades in the making, but now Rice University biochemist John Olson and his colleagues have found that deep-diving mammals have a more stable version of myoglobin, a protein that holds oxygen for use inside muscle cells.
This allows whales to produce larger amounts of myoglobin than humans, Olson explained in a statement. In fact, the creatures can pack 10 to 20 times more of this protein into their muscles than a human. This allows them to “download” oxygen directly into their skeletal muscles and stay active, even when they are holding their breath at great depths, he added.
“Whale meat is so dark because it’s filled with myoglobin that is capable of holding oxygen. But when the myoglobin is newly made, it does not yet contain heme, an iron-filled compound that forms the nonprotein part of hemoglobin,” said Olson. “We found that the stability of heme-free myoglobin is the key factor that allows cells to produce high amounts of the protein.”
Olson has spent 20 years studying hemoglobin, a larger and more complex oxygen-transporting protein found in blood, with the goal of creating synthetic blood for use in transfusions. He wants to create a strain of bacteria capable of generating massive amounts of this protein, and now he is one step closer to that goal thanks to this new discovery.
Myoglobin stability is the key, researchers find
Currently, hospitals and emergency rooms are forced to depend upon donated blood, which tends to be in short supply and can only be stored for a limited amount of time. In order to make longer lasting and more readily available synthetic blood, Olson and his fellow researchers hope to max out the amount of hemoglobin that bacteria can express.
“Our results confirm that protein stability is the key,” he said. His team “developed an in-vitro method for testing myoglobin expression outside of living cells. That allowed us to carefully control all the variables. We found that the amount of fully active myoglobin expressed was directly and strongly dependent on the stability of the protein before it bound the heme group.”
The globin family of proteins are shaped like the pocket of a baseball glove, opening and closing in order to trap and release oxygen, the study authors explained. The more stable that the heme-free type of myoglobin they could produce, the greater amount of the final product they could create.
During their experiments, the researchers compared the stability and cell-free expression level of myoglobins from humans, pigs, gray seals and several types of whales, confirming that stability of the heme-free version directly correlated with expression levels. Olson said that the discovery was “very important for our projects on synthetic blood substitutes.”
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