Ultra-Stability of Heme-Free Myoglobin in Deep-Diving Whales Is Clue to Engineering Bacteria That Can Produce Abundant Hemoglobin for Use in Synthetic Human Blood Substitutes

The ultra-stable properties of the proteins that allow deep-diving whales to remain active while holding their breath for up to two hours could help Rice University biochemist Dr. John Olson and his colleagues finish a 20-year quest to create lifesaving synthetic blood for human trauma patients. In a new study featured as one of two papers of the week in the September 25, 2015 issue of the Journal of Biological Chemistry, Dr. Olson and colleagues Dr. George Phillips, Dr. Lucian Smith, and Premila Samuel compared the muscle protein myoglobin from humans, whales, and other deep-diving mammals. The article is titled "Apoglobin Stability Is the Major Factor Governing Both Cell-Free and In Vivo Expression of Holomyoglobin." 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. The researchers found that stability was the key for cells to make large amounts of myoglobin, which is 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 Dr. Olson, Rice's Ralph and Dorothy Looney Professor of Biochemistry and Cell Biology. "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." This finding is important to Dr.
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