Abstract
1. Haemoglobin, dissolved in an isotonic KCl-solution, was heated to various extent at its isoelectric region, and the buffering power of the denatured as well as of the coagulated haemoglobin was studied.
2. Ilaemoglobin, when heated at its isoelectric region, denatures first in a soluble state before its molecular aggregation, i.e. coagulation takes place, and its buffering power increases parallel to its denaturation to a certain extent. When the haemoglobin is denatured more intensively by heating, however, its buffering power begins to shift in the opposite direction despite the ceaseless decrease in its O2-capacity. Accordingly, the extent of denaturation of haemoglobin is represented more reasonably by the decrease in its O2-combining ability than by the increase in its buffering power.
3. When a haemoglobin solution is heated at about 52°C for several hours at its isoelectric region, its pH value shifts only about 0.02 pH towards the alkaline side.
4. Coagulation of haemoglobin, produced by heating at its isoelectric region, decreases in its buffering power, which decrease proceeds further in proportion to their intensity of heating.
5. Denaturation of haemoglobin, taking place during the process of its preparation causes a diminution in its buffering power.
