Hemoglobin-water interactions in normal and sickle erythrocytes by proton magnetic resonance T1 ϱ measurements

Abstract

The dependence of the water proton magnetic resonance spin-lattice relaxation rate ( T 1 ϱ −1) in the rotating frame on the strength of the spin-locking ( H 1) field has been investigated for packed oxy and deoxy normal and sickle erythrocytes at temperatures from 9 to 40 °C. The T 1 ϱ −1 of oxy or deoxy normal erythrocytes shows no dependence on H 1 up to ~7 G at any temperature studied. On the other hand, T 1 ϱ −1 decreases from about 40 s −1 to 15 s −1 ( H 1 from 0 to ~7 G) for deoxygenated packed sickle cells at 40 °C. The magnitude of this variation of T 1 ϱ −1 with H 1 decreases with decreasing temperature. Oxy packed sickle cells also show a dependence of T 1 ϱ −1 on H 1 but the magnitude is <10% of that of the deoxygenated samples. These results suggest that water proton T 1 ϱ −1 measurements are a sensitive probe of hemoglobin S polymerization and provide a novel technique for the study of slow water motions in these systems. The T 1 ϱ −1 results are compared with low frequency T 1 −1 results of other investigators on hemoglobin S solutions. Analysis of the data suggests that water proton motions with correlation times of the order of 10 −5 s are present in the deoxygenated sickle cell samples at temperatures above 10 °C.