Interactions between hemoglobin and organic phosphates investigated with 31P nuclear magnetic resonance spectroscopy and ultrafiltration.
1. The chemical shifts (delta) of the phosphates of 2,3-diphosphoglycerate and adenosine triphosphate (ATP) were determined by phosphorus nuclear magnetic resonance (31P NMR) spectroscopy and were found to be displaced downfield following the addition of hemoglobin (3 mM) to a solution of either diphosphoglycerate (5 mM) or ATP (1 mM). 2. The binding of these compounds to hemoglobin was also determined by membrane ultrafiltration. A direct relationship was observed between the change in chemical shift ((delta delta) of the 2-P and 3-P of diphosphoglycerate and the percent diphosphoglycerate bound, when the latter was varied by altering pH, oxygenation state, or total diphosphoglycerate concentration. 3. In comparable studies with ATP binding, a linear relationship between the delta delta values of the gamma-, beta-, and alpha-P of ATP and the percent of ATP bound was not observed when the data from all of the experiments were plotted. NMR signals were not detectible in deoxyhemoglobin solutions containing 1 mM ATP but were seen in solutions containing 3.8 mM ATP. 4. The results indicate that 31P NMR spectroscopy is a promising tool for investigating organic phosphate interactions with hemoglobin.
Interactions between hemoglobin and organic phosphates investigated with 31P nuclear magnetic resonance spectroscopy and ultrafiltration. 1. The chemical shifts (delta) of the phosphates of 2,3-diphosphoglycerate and adenosine triphosphate (ATP) were determined by phosphorus nuclear magnetic resonance (31P NMR) spectroscopy and were found to be displaced downfield following the addition of hemoglobin (3 mM) to a solution of either diphosphoglycerate (5 mM) or ATP (1 mM). 2. The binding of these compounds to hemoglobin was also determined by membrane ultrafiltration. A direct relationship was observed between the change in chemical shift ((delta delta) of the 2-P and 3-P of diphosphoglycerate and the percent diphosphoglycerate bound, when the latter was varied by altering pH, oxygenation state, or total diphosphoglycerate concentration. 3. In comparable studies with ATP binding, a linear relationship between the delta delta values of the gamma-, beta-, and alpha-P of ATP and the percent of ATP bound was not observed when the data from all of the experiments were plotted. NMR signals were not detectible in deoxyhemoglobin solutions containing 1 mM ATP but were seen in solutions containing 3.8 mM ATP. 4. The results indicate that 31P NMR spectroscopy is a promising tool for investigating organic phosphate interactions with hemoglobin.