Kinetic characterization of myoglobins from vertebrates with vastly different body temperatures.

Fish myoglobins are structurally distinct from the previously characterized mammalian myoglobins. Teleost fishes express generally lower levels of myoglobin than those found in mammals. Although the oxygen binding affinity is essentially the same as mammalian myoglobins, oxygen dissociation rates and carbon monoxide combination rates of the teleost myoglobins studied are significantly faster. Thus, the kinetic parameters of myoglobin from two Antarctic teleost species, measured close to their body temperature of -1 degree C, are comparable to those of mammalian myoglobins with higher body temperatures. These data suggest myoglobins from Antarctic teleosts may function at extreme environmental temperatures.