Structure and stability of the molybdenum cofactor intermediate cyclic pyranopterin monophosphate
Structure and stability of the molybdenum cofactor intermediate cyclic pyranopterin monophosphate
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DOI：
10.1007/s00775-011-0835-2
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发表时间：
2012-01-01
影响因子：
3
通讯作者：
Schwarz, Guenter
中科院分区：
文献类型：
--
作者：
Santamaria-Araujo, Jose Angel;Wray, Victor;Schwarz, Guenter
氢化(还原)蝶呤存在于所有生物体中，它们参与关键的代谢过程。钼的生物活性形式与一种被称为金属结合蝶呤(MPT)的完全还原的四氢吡喃喋呤结合，形成所谓的钼辅助因子(MOCO)。环状吡喃蝶呤单磷酸盐(CPMP)是钼辅因子生物合成的第一个可分离中间体。在这里，我们首次提出了一个活性的MoCO中间体的C-13核磁共振表征。CPMP的~(13)C核磁共振数据证实了先前的数据，表明cPMP的四氢吡喃喋呤性质以及侧链的C1‘位置上存在宝石二醇。宝石二醇的稳定性，以及在低场(175-220ppm)下没有任何可观察到的信号，表明宝石二醇不是一种化学人工产物，但在化学上是稳定的，并且与酮式不平衡。最后，我们用分光光度法研究了金属中心、络合剂、不同缓冲液和pH值对cPMP氧化动力学的影响。我们发现氧化是依赖于金属的，并且在EDTA的存在下可以显著地延缓氧化。
Hydrogenated (reduced) pterins are found in all living organisms, where they are involved in key metabolic processes. Molybdenum in its biologically active form is bound to a fully reduced tetrahydropyranopterin referred to as a metal-binding pterin (MPT), forming the so-called molybdenum cofactor (Moco). Cyclic pyranopterin monophosphate (cPMP) is the first isolatable intermediate in molybdenum cofactor biosynthesis. Here we present for the first time a C-13 NMR characterization of an active Moco intermediate. The C-13 NMR data for cPMP corroborate previous data showing the tetrahydropyranopterin nature of cPMP and the presence of a gem-diol in the C1' position of the side chain. The stability of the gem-diol, together with the absence of any observable signal at low field (175-220 ppm), is an indication that the gem-diol is not a chemical artifact, but is chemically stable and not in equilibrium with the keto form. Finally, we have studied spectrophotometrically the kinetics of cPMP oxidation in the presence of metal centers, chelating agents, and different buffers and pH values. We found that oxidation is metal-dependent and can be substantially retarded in the presence of EDTA.