Continuous gas-depletion technique for measuring O2-dissociation curves of high-affinity hemoglobins

The O2-depletion technique allows a continuous measurement of the complete O2-dissociation curve of high-affinity hemoglobins in the O2-partial pressure range of 700 to 10(-4) mm Hg. With this technique p50 values greater than or equal to 0.01 mm Hg (approximately equal to 1.3 Pa) can be determined for 3-microliter hemoglobin samples. As examples, O2-dissociation curves of sperm whale myoglobin (p50 = 0.9 mm Hg, 25 degrees C, pH 8.0) and Dicrocoelium hemoglobin (p50 = 0.06 mm Hg, 25 degrees C, pH 4.9) are demonstrated which show Hill coefficients of n = 1.0 over the complete O2-saturation range.