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Their ''hypothesis'' was that whales and other aquatic animals can hold their breath for so long because they can store more oxygen in their muscles by increasing the concentration of myoglobin in each muscle cells. Specifically, they predicted that species could increase the concentration of myoglobin by increasing its solubility through increasing the net charge, so that there would be repulsion between the myoglobin protein even at high concentrations, which would prevent aggregation and precipitation. | Their ''hypothesis'' was that whales and other aquatic animals can hold their breath for so long because they can store more oxygen in their muscles by increasing the concentration of myoglobin in each muscle cells. Specifically, they predicted that species could increase the concentration of myoglobin by increasing its solubility through increasing the net charge, so that there would be repulsion between the myoglobin protein even at high concentrations, which would prevent aggregation and precipitation. | ||
Amazingly, they found an association between an animals' ability to hold its breath, high concentrations of myoglobin in muscle tissue, and a larger positive net charge of myoglobin. Typically, purified terrestrial mammal's myoglobin has a solubility of 20 mg/g in an aqueous solution at neutral pH ([[http://www.sigmaaldrich.com/content/dam/sigma-aldrich/docs/Sigma/Product_Information_Sheet/2/m0630pis.pdf Sigma Aldrich]]) which turns out to be the maximum level of myoglobin found in most terrestrial mammal's tissue. But whales and other aquatic mammals far exceed this solubility limit, e.g., whales have 70 mg/g. The way that they overcome the solubility constraint may be traced back to a modest increase in the net charge of myoglobin - from around +2 in terrestrial animals to around +4 in aquatic animals. | Amazingly, ''they found an association between an animals' ability to hold its breath, high concentrations of myoglobin in muscle tissue, and a larger positive net charge of myoglobin''. Typically, purified terrestrial mammal's myoglobin has a solubility of 20 mg/g in an aqueous solution at neutral pH ([[http://www.sigmaaldrich.com/content/dam/sigma-aldrich/docs/Sigma/Product_Information_Sheet/2/m0630pis.pdf Sigma Aldrich]]) which turns out to be the maximum level of myoglobin found in most terrestrial mammal's tissue. But whales and other aquatic mammals far exceed this solubility limit, e.g., whales have 70 mg/g. The way that they overcome the solubility constraint may be traced back to a modest increase in the net charge of myoglobin - from around +2 in terrestrial animals to around +4 in aquatic animals. | ||
<StructureSection load='1mbn' size='350' side='right' caption='myoglobin (PDB entry [[1mbn]])' scene='57/575026/Electrostatics/10'> | <StructureSection load='1mbn' size='350' side='right' caption='myoglobin (PDB entry [[1mbn]])' scene='57/575026/Electrostatics/10'> | ||