Brown urine is found in patients with rhabdomyolysis because this protein is being broken down.
In mass spectrometry, this protein, obtained from horse hearts, is a common calibration standard. In humans but not other animals, this protein has a cysteine at residue 110 that is nitrosylated by nitric oxide, making this protein a "scavenger" of nitric oxide. Brown urine is found in patients with rhabdomyolysis because this protein is being broken down. It was isolated from sperm whales by John Kendrew and was the first protein to be targeted by X-ray crystallography. It has a Hill coefficient of 1, a p50 of 2.8 torr, and a hyperbolic-shaped dissociation curve which is independent of pH. The ability of this protein to bind substrate tightly even at low partial pressure enhances the deep-sea diving ability of marine mammals. For 10 points, name this protein that transports oxygen in muscles.
In mass spectrometry, this protein, obtained from horse hearts, is a common calibration standard.
myoglobin [do not accept or prompt on "hemoglobin"]