Gopinath Purushothaman, Ramalingam Vijayakumar, Breslow Ronald
Department of Chemistry, Columbia University, New York, NY 10027.
Department of Chemistry, Columbia University, New York, NY 10027
Proc Natl Acad Sci U S A. 2015 Sep 29;112(39):12011-4. doi: 10.1073/pnas.1516239112. Epub 2015 Sep 14.
Derivatives of ribosyl pyrophosphate have been synthesized, and examined with magnesium salts in the coupling of the ribose unit to various nucleophiles, including pyrazole and 2-chloroimidazole. Only with the magnesium salt present did they generate the ribosyl cation by binding to the leaving group and then couple the ribose derivative with nucleophiles. The role of magnesium salts in phosphorylation of methanol by ATP was also examined. Here a remarkable effect was seen: phosphorylation by ATP was slowed with low concentrations of Mg(2+) but accelerated by higher concentrations. Related effects were also seen in the effect of Mg(2+) on phosphorylation by ADP. The likely mechanisms explain these effects.
核糖焦磷酸的衍生物已被合成,并在核糖单元与各种亲核试剂(包括吡唑和2-氯咪唑)的偶联反应中与镁盐一起进行了研究。只有在存在镁盐的情况下,它们才会通过与离去基团结合而生成核糖阳离子,然后将核糖衍生物与亲核试剂偶联。还研究了镁盐在ATP使甲醇磷酸化反应中的作用。在这里观察到了一个显著的效果:低浓度的Mg(2+)会减缓ATP的磷酸化作用,但高浓度的Mg(2+)会加速该反应。在Mg(2+)对ADP磷酸化作用的影响中也观察到了相关效应。可能的机理解释了这些效应。