De O₂ bindende eigenschappen van het haemoglobine en aspecten van Hb-heterogeniteit van <i>Pleuronectus platessa</i> L. en <i>Pleuronectus flesus</i> L

1. A comparative study was made of the oxygenation properties of haemoglobine (Hb) from plaice Pleuronectus platessa L. and of flounder (Pleuronectus flesus L.)2. The multiple haemoglobins in each species were separated by means of iso-electric focusing and oxygen binding properties of the main component haemoglobins were determined. 3. The oxygen affinity of whole blood, measured directly after collection is higher in plaice than in flounder, under the same conditions of pH and temperature. Removal of the blood plasma lowers the oxygen affinity of the haemoglobin in the erythrocytes. This shift is less pronounced in the flounder than in plaice and corresponds with dilution effects of the Hb and intracellular factors such as the organic phosphates 4. The isolated Hb components of plaice showed small mutual differences in oxygen affinity at the same pH's and temperatures. These differences were not found to be significant.5. The Bohr effect for the washed red cells and for Hb in solution of plaice and flounder, and for the six main components of plaice. The Bohr effect, expressed as Delta log P50/Delta pH, of plaice erythrocytes and of Hb in solution were -0,64 and -0,78 respectively; for flounder the corresponding values were -0,53 and -0,45. The Bohr factor for the six components of plaice Hb varied from -1,26 to -1,43.6. The overall temperature influence, expressed in terms of the apparent heat of oxygenation, delta H, amounted to -1,14 and -16,6 kcal/mole respectively for erythrocytes and Hb solution of plaice. For flounder the corresponding values found were -15,1 and -19,1 kcal/mole. For five of the main Hb components of plaice the delta H values varied from -14,5 to -17,0 kcal/mole