Structure and function in sea turtle hemoglobins.

Using time resolved resonance Raman spectroscopy we have been able to compare the internal structure of oxygenated hemoglobin from several different sea turtles to that in hemoglobin from a variety of other organisms including fresh water turtles, several fish, an aquatic snake (Acrochordus javanicus) and two mammals. We have focussed upon the linkage between the iron and the proximal histidine, a structural parameter which has been related to the reactivity of the heme towards oxygen. We find that sea turtle hemoglobins are distinctly unusual, having an oxygen binding site that remains highly strained under all physiological conditions.