Intracellular pH measurements by 31P nuclear magnetic resonance. Influence of factors other than pH on 31P chemical shifts.
Intracellular pH measurements by 31P nuclear magnetic resonance. Influence of factors other than pH on 31P chemical shifts.
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DOI：
10.1021/bi00522a006
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发表时间：
1981-09
期刊：
影响因子：
2.9
通讯作者：
Justin K. M. Roberts;N. Wade-Jardetzky;O. Jardetsky
中科院分区：
文献类型：
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作者：
Justin K. M. Roberts;N. Wade-Jardetzky;O. Jardetsky
给出了无机磷酸盐和葡萄糖6-磷酸盐在不同组成溶液中的化学位移与pH的滴定曲线。显示K+（0.1M）和Mg 2+（5 mM）的生理浓度显著地移动滴定曲线。Mg 2+的作用可以通过加入足够量的三磷酸腺苷或有机酸而部分或完全逆转。酸性蛋白质牛血清白蛋白和可溶性玉米根尖蛋白对滴定曲线无明显影响，碱性蛋白质鱼精蛋白对滴定曲线有显著影响。结果清楚地表明，如果通过31 P NMR测定细胞内pH值被认为在+/- 0.05-01 pH单位内准确，则需要了解样品中的细胞内离子强度和游离Mg 2+浓度。
Titration curves plotting chemical shift vs. pH for inorganic phosphate and glucose 6-phosphate in solutions of various composition are presented. Physiological concentrations of K+ (0.1 M) and Mg2+ (5 mM) are shown to significantly shift the titration curve. The Mg2+ effect can be partly or completely reversed by addition of sufficient quantities of adenosine triphosphate or organic acids. The acidic protein bovine serum albumin and soluble maize root tip protein have no noticeable effect on the titration curves, whereas the basic protein protamine exerts a profound effect. The results clearly indicate that knowledge of intracellular ionic strength and free Mg2+ concentrations in the sample are required if the determination of intracellular pH by 31P NMR is to be considered accurate within +/- 0.05-01 pH unit.