31P NMR relaxation time studies of 2,3-diphosphoglycerate in solution and intact erythrocytes.

The 31P T1 spin-lattice relaxation times and nuclear Overhauser effects of 3-P and 2-P in 2,3-diphosphoglycerate (2,3-DPG) have been measured in pure water solutions and in suspensions of intact erythrocytes. It was found that extremely careful purification of the water solutions from paramagnetic impurities was necessary in order to obtain reproducible results. The dominant relaxation mechanism in purified samples was shown to be the dipole-dipole interaction. Contributions from the chemical-shift anisotropy mechanism were demonstrated to be important at higher magnetic field strengths. Based upon the measurements in water solutions and intact erythrocyte suspensions it was concluded that there could be observed no significant influence of the oxygenation state of hemoglobin on the 31P T1 values of 2,3-DPG.