MEASUREMENT OF THE DISSOCIATION-CONSTANT OF MGATP AT PHYSIOLOGICAL NUCLEOTIDE LEVELS BY A COMBINATION OF P-31 NMR AND OPTICAL ABSORBANCE SPECTROSCOPY
MEASUREMENT OF THE DISSOCIATION-CONSTANT OF MGATP AT PHYSIOLOGICAL NUCLEOTIDE LEVELS BY A COMBINATION OF P-31 NMR AND OPTICAL ABSORBANCE SPECTROSCOPY
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DOI：
10.1016/0006-291x(83)91562-0
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发表时间：
1983-01-01
影响因子：
3.1
通讯作者：
ROSE, ZB
中科院分区：
文献类型：
--
作者：
GUPTA, RK;GUPTA, P;ROSE, ZB
为了解决文献中关于在无创31P核磁共振程序中用于测定活细胞内游离镁离子的镁与三磷酸腺苷的亲和力的争议，用核磁共振和光吸收技术相结合的方法重新研究了生理离子条件下和细胞内三磷酸腺苷浓度范围内镁三磷酸腺苷的表观Kd。新的组合方法利用31P核磁共振化学位移来确定ATP在含有游离三磷酸腺苷和镁三磷酸腺苷的溶液中与镁离子的络合程度，并使用适当校准的指示剂安替比拉偶氮III来光学测量同一溶液中的游离镁离子。数据得出的平均值为50.+-。10微米为镁三磷酸腺苷的表观Kd值，这表明在几种不同类型的组织中，包括灌流的心肌中，游离镁离子的水平较低，与最近的文献报道相反。
To resolve a controversy in the literature concerning the affinity of Mg2+ for ATP to be used in a noninvasive 31P NMR procedure for the determination of free Mg2+ in living cells, the apparent Kd of MgATP was reinvestigated under physiologic ionic conditions and over the cellular range of ATP concentrations by a combination of NMR and optical absorbance techniques. The new combination method utilizes 31P NMR chemical shifts to determine the degree of Mg2+ chelation of ATP in a solution containing free ATP and MgATP, and uses a properly calibrated indicator dye, antipyrylazo III, for optical measurement of free Mg2+ in the same solution. The data yield an average value of 50 .+-. 10 .mu.M for the apparent Kd of MgATP which indicates low levels of free Mg2+ (< 1 mM) in several different types of tissues, including perfused heart muscle, contrary to a recent report in the literature.