The determination of the free magnesium level in the human red blood cell by 31P NMR.
The determination of the free magnesium level in the human red blood cell by 31P NMR.
复制标题
通过 31P NMR 测定人红细胞中的游离镁水平。
DOI：
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发表时间：
1978
影响因子：
4.8
通讯作者：
Z. B. Rose
中科院分区：
文献类型：
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作者：
R. Gupta;J. Benovic;Z. B. Rose
在完全有氧和无氧条件下，在37 ℃，含5%CO2的气氛中，糖酵解人红细胞胞内ATP的磷NMR谱已被获得并定量。将细胞内ATP的α P和β P共振与α-β和β-γ 31 P自旋-自旋耦合常数之间的分离与适当的对照进行比较，直接揭示了在细胞的有氧和厌氧状态下，总ATP的84 +/-4%和78 +/-4%分别与Mg 2+络合。由于游离和复合ATP在NMR时间尺度上的快速交换，该测定不能区分溶液中游离的分子和与血红蛋白结合的分子。根据这些数据和各种磷酸化代谢物与血红蛋白和Mg 2+相互作用的现有知识，在正常红细胞样品中，游离Mg 2+的细胞内浓度在需氧状态下测定为0.25 +/- 0.07 mM，在厌氧状态下测定为0.67 +/- 0.15 mM。游离Mg 2+的知识允许ATP，ADP，甘油酸-2，3-P2，血红蛋白之间的自由和复合形式的分布的计算。结果表明，即使在需氧细胞中，也有约40%的甘油酸-2，3-P2和ATP与血红蛋白复合，而在完全厌氧细胞中，分别有约90%和约60%与血红蛋白复合。游离ATP的水平在厌氧条件下降低3倍，而MgATP的变化很小。脱氧后MgADP的细胞内水平增加约2倍。由于红细胞中的Mg 2+主要是络合的，因此在完全厌氧条件下游离Mg 2+增加3倍将显著影响酶促反应的速率。
The phosphorus NMR spectra of intracellular ATP in glycolyzing human red blood cells maintained at 37 degrees C in an atmosphere containing 5% CO2 have been obtained and quantitated under completely aerobic and anaerobic conditions. A comparison of the separation between the alphaP and betaP resonances and the alpha-beta and beta-gamma 31P spin-spin coupling constants of intracellular ATP with appropriate controls directly reveals that 84 +/- 4% and 78 +/- 4% of the total ATP are complexed to Mg2+ in the aerobic and anaerobic states of the cell, respectively. This determination does not differentiate between molecules free in solution and those bound to hemoglobin due to rapid exchange on the NMR time scale of free and complexed ATP. From these data and the prior knowledge of the interactions of various phosphorylated metabolites with hemoglobin and Mg2+, the intracellular concentration of free Mg2+ is determined to be 0.25 +/- 0.07 mM in the aerobic and 0.67 +/- 0.15 mM in the anaerobic state in a sample of normal red blood cells. Knowledge of free Mg2+ permitted a calculation of the distribution of ATP, ADP, glycerate-2,3-P2, and hemoglobin among their free and complexed forms. The results indicate that approximately 40% of the glycerate-2,3-P2 and ATP are complexed to hemoglobin even in aerobic cells and approximately 90% and approximately 60%, respectively, in completely anaerobic cells. The level of free ATP decreases 3-fold anaerobically whereas the MgATP changes very little. The intracellular level of MgADP increases about 2-fold upon deoxygenation. Since the Mg2+ in the red cell is largely complexed, the 3-fold increase in free Mg2+ under fully anaerobic conditions would significantly affect the rates of enzymatic reactions.