Arctic life and adaptation—III. the function of whale ( Balaenoptera acutorostrata) hemoglobin

Abstract

1. 1. The oxygen binding properties of the hemoglobin from the Lesser Rorqual, Balaenoptera acutorostrata, has been investigated with respect to the possible effects of organic phosphates on gas transport in arctic environments. 2. 2. The intrinsic oxygen affinity of the hemoglobin is high and strongly modulated by the effects of organic phoshates. 3. 3. In the absence of organic phosphates, the temperature sensitivity of oxygen binding expressed by the heat of oxygenation, ΔH is − 16.2 kcal/mol when corrected for the heat of oxygen in solution. 4. 4. In the presence of organic phosphates there is a marked decreased in the temperature sensitivity ΔH ∼ − 5 kcal/mol) . 5. 5. This feature is of great importance for oxygen unloading in the flippers and the tail, where the temperature is lower than the trunk of the whale. 6. 6. Furthermore the organic phoshates strongly increase the Bohr coefficient, Δlog P 50/Δ pH , from less than −0.3 in stripped hemoglobin to about −1.5 when the hemoglobin is saturated with P 6-inositol. 7. 7. This feature may be of great physiological importance by reducing the CO 2 tension and acidosis after a prolonged dive.