What's the link between whales and synthetic blood?

Have you ever been curious about why the whales can dive so deeply in such a long time? It is the ultra-stable properties of the proteins that allow deep-diving whales to remain active while holding their breath for up to two hours. The findings just helped Rice University's Ralph and Dorothy Looney Professor of Biochemistry and Cell Biology and his colleagues finish a significance goal to create lifesaving synthetic blood for human trauma patients.
Olson and colleagues George Phillips, Lucian Smith and Premila Samuel compared the muscle protein myoglobin from humans, whales and other deep-diving mammals in the new study they published in the Journal of Biological Chemistry this week. Myoglobin holds oxygen for ready use inside muscle cells, and the study found that marine mammals have ultra-stable versions of myoglobin that tend not to unfold. It was found that stability was the key for cells to make large amounts of myoglobin, which explains why deep-diving mammals can load their muscle cells with far more myoglobin than humans.
"Whales and other deep-diving marine mammals can pack 10-20 times more myoglobin into their cells than humans can, and that allows them to 'download' oxygen directly into their skeletal muscles and stay active even when they are holding their breath," said Olson. "The reason whale meat is so dark is that it's filled with myoglobin that is capable of holding oxygen. But when the myoglobin is newly made, it does not yet contain heme. We found that the stability of heme-free myoglobin is the key factor that allows cells to produce high amounts of myoglobin."
Olson wants to create a strain of bacteria that can generate massive quantities of another protein that's closely related to myoglobin. In the last 20 years, Olson had been working on a larger, more complex oxygen-carrying protein in blood - hemoglobin. His goal was to create synthetic blood for use in transfusions. So far, hospitals and trauma specialists are relying on donated whole blood. But this kind of blood is often in short supply and only can store in a short time. One of the hopes in Olson's plan is to maximize the hemoglobin that a bacterium can express.
The results shows suggest that protein stability is the key. In the research, the amount of fully active myoglobin expressed was directly and strongly dependent on the stability of the protein before it bound the heme group.
In 2013, Michael Berenbrink from Liverpool University and Kevin Campbell from the University of Manitoba noted that deep-diving mammals expressed large amounts of myoglobin in their muscle tissue. They analyzed the genes and available information for all mammalian myoglobins, including those from deep-diving species and found that the myoglobins from aquatic mammals had large positive surface charges compared with those from land animals. They assumed that the charge differences allowed the aquatic species to pack more myoglobin into their muscle cells.
Scientists later did some tests and compared the stability and cell-free expression level of myoglobins from humans, pigs, goosebeak whales, gray seals, sperm whales, dwarf sperm whales and the three mutants, which had low heme affinity but were 50 times more stable than apomyoglobins from the whales. The results showed that the stability of apoprotein is directly correlated with expression levels.
According to Olson, the results of the study clearly verify the expression-stability correlations that had been anecdotally observed in previous work in both mammalian cells and E. coli.
The findings are so important to the projects on synthetic blood substitutes and determining the toxicity of acellular hemoglobin. It is a big step to in the process of creating lifesaving synthetic blood for human trauma patients.
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