Effect of oxygen concentration on trasverse water proton relaxation times in erythrocytes homozygous and heterozygous for hemoglonin S.

The transverse water proton relaxation times (T₂) of erythrocytes homozygous and heterozygous for hemoglobin S have been measured as a function of oxyhemoglobin concentration at 37 °C. An immediate decrease in T₂ is observed in S/S erythrocytes as the amount of oxyhemoglobin is decreased and the maximum change is observed at 50% deoxyhemoglobin S. In heterozygous erythrocytes, the T₂ remains unchanged until a critical level of deoxyhemoglobin is attained. The critical level of deoxyhemoglobin is a function of the percentage of hemoglobin S in the heterozygous erythrocytes. A Hill plot of the data obtained from S/S erythrocytes gives an n value of around 2.4. These results suggest that the measurement of T₂ is sensitive to the very early stages of the polymerization process. This suggestion is supported by calculations; our T₂ measurements are sensitive to a range of correlation times expected for hemoglobin monomers at one extreme and linear polymers of seven hemoglobin molecules at the other extreme.