Functional properties of hemoglobins from Triturus cristatus

The functional properties of hemoglobins from Triturus cristatus carnifex have been characterized both from an equilibrium and a kinetic point of view. A special attention has been given to the effect of organic phosphates in view of their role in the modulation of the hemoglobin function. Under stripped conditions newt hemoglobins display a negative Bohr effect which becomes much less pronounced in the presence of 0.2 M inorganic phosphates. The effect of organic phosphates involves not only a drop in the O2 affinity but also a large change in the shape of the O2 Bohr effect which becomes markedly positive in the presence of myo-inositol hexakis(phosphate). The experimental data reported make it possible to give a complete picture of the functional behaviour of newt hemoglobins, making a contribution to clarifying the dependence of the sign of the Bohr effect on the acclimatization temperature of the animals that has been previously reported [Morpurgo, G., Battaglia, P. A. and Leggio, T. (1970) Nature (Lond.) 225, 76--77].