Complex formation between magnesium ions and pyridine nucleotide coenzymes.
Complex formation between magnesium ions and pyridine nucleotide coenzymes.
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镁离子和吡啶核苷酸辅酶之间形成复合物。
DOI：
10.1016/0304-4165(73)90319-x
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发表时间：
1973
期刊：
影响因子：
--
通讯作者：
D. Apps
中科院分区：
文献类型：
--
作者：
D. Apps
用多种独立的方法测定了镁离子与吡啶核苷酸辅酶形成的二元络合物的离解常数。在8-羟基喹啉存在下，镁离子与NAD+进行分光光度滴定，辅酶与镁离子进行分子排斥层析，得到NAD+的离解常数约为20 mM。镁离子络合物。镁离子和DEAE-Sephadex之间的配体竞争表明，与NADH和NADP+的相应络合物的解离常数值相似。然而，用镁离子荧光滴定NADH的离解常数要小得多(0.01 mm)，这可能是因为这些实验必须在甲醇水中进行。推测镁离子可能与吡啶核苷酸辅酶中的焦磷酸基团结合。这一结果与酶动力学研究的推论一致。
The dissociation constants of binary complexes formed between Mg2+and pyridine nucleotide coenzymes have been measured by a number of independent methods. Spectrophotometric titration of NAD+with Mg2+in the presence of 8-hydroxyquinoline, and molecular exclusion chromatography of the coenzyme with Mg2+, agree on a value of about 20 mM for the dissociation constant of the NAD+. Mg2+complex. Ligand competition between Mg2+and DEAE-Sephadex indicates a similar value of the dissociation constant, for the corresponding complexes with NADH and NADP+. However fluorimetric titration of NADH with Mg2+gives a much lower dissociation constant (0.01 mM), possibly because these experiments were necessarily performed in aqueous methanol. It is concluded that the Mg2+probably binds to the pyrophosphate grouping in pyridine nucleotide coenzymes. The results are in accord with inferences drawn from enzyme kinetic studies.