The effects of temperature, pH, and magnesium on the diffusion coefficient of ATP in solutions of physiological ionic strength
The effects of temperature, pH, and magnesium on the diffusion coefficient of ATP in solutions of physiological ionic strength
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DOI：
10.1016/0304-4165(96)00053-0
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发表时间：
1996-10-24
影响因子：
3
通讯作者：
Moerland, TS
中科院分区：
文献类型：
--
作者：
Hubley, MJ;Locke, BR;Moerland, TS
三磷酸腺苷（ATP）的细胞内扩散转运对细胞代谢至关重要。物理模型预测小分子的扩散系数（D）是扩散环境的温度和粘度的函数。因此，变温动物通常经历的体温变化预计会导致细胞内ATP转运速率的变化。然而，它已被假定，在ATP的电荷的变化可能会影响ATP和胞质溶胶之间的相互作用和D-ATP的温度敏感性可能偏离预测的关系。为了研究电荷变化对D-ATP温度敏感性的影响，我们在不同的温度、pH和pMg（2+）条件下测量了D-ATP。pH和pMg（2+）的变化被用来改变ATP的净电荷，并在生理离子强度的溶液中测量D-ATP。结果表明，D-ATP与温度呈正相关，D-ATP=1.75 ± 0.09，3.68 ± 0.14。和4.64+/-0.13（平均值+/- S.E.M）x 10（-6）cm（2）/s。pH值和pMg（2+）的变化对D-ATP没有显著影响，D-ATP随温度的变化与根据水介质的温度和粘度变化预测的结果相似。
Intracellular diffusive transport of adenosine triphosphate (ATP) is critical to cellular metabolism. Physical models predict that diffusion coefficients (D) of small molecules are functions of temperature and viscosity of the diffusive environment. Therefore, changes, in body temperature, commonly experienced by poikilotherms, are expected to result in changes in the rate of intracellular ATP transport. However, it has been postulated that changes in the electrical charge of ATP may influence the interaction between ATP and the cytosol and that the temperature sensitivity of D-ATP may deviate from the predicted relationship. To investigate the effects of changes in electrical charge on the temperature sensitivity of D-ATP, we measured D-ATP under various conditions of temperature, pH, and pMg(2+). Changes in pH and pMg(2+) were used to alter the net charge of ATP, and D-ATP was measured in solutions of physiological ionic strength. Results showed a positive correlation between D-ATP and temperature; D-ATP=1.75+/-0.09, 3.68+/-0.14. and 4.64+/-0.13 (mean +/- S.E.M) x 10(-6) cm(2)/s at 5 degrees C, 25 degrees C, and 40 degrees C, respectively. Changes in pH and pMg(2+) did not significantly influence D-ATP, and the change in D-ATP with respect to temperature was similar to that predicted on the basis of changes in temperature and viscosity of the aqueous medium.