KINETIC CHARACTERIZATION OF MYOGLOBINS FROM VERTEBRATES WITH VASTLY DIFFERENT BODY TEMPERATURES

Fish myoglobins are structurally distinct from the previously characte rized mammalian myoglobins. Teleost fishes express generally lower lev els of myoglobin than those found in mammals. Although the oxygen bind ing affinity is essentially the same as mammalian myoglobins, oxygen d issociation rates and carbon monoxide combination rates of the teleost myoglobins studied are significantly faster. Thus, the kinetic parame ters of myoglobin from two Antarctic teleost species, measured close t o their body temperature of -1 degrees C, are comparable to those of m ammalian myoglobins with higher body temperatures. These data suggest myoglobins from Antarctic teleosts may function at extreme environment al temperatures. (C) 1997 Elsevier Science Inc.